Great thread topic. Not South America, but I think our experience is applicable to anyone near the equator.
Two people in good health for 18 months traveling around, based on Uganda - South Sudan border. Our primary location is a basic compound (water tower, but no electricity) and more than three hours from closest grocery store. Brought eight North Face Base Camp Bags worth of stuff. I'll list the "loved," "hated," and "wasted"... hopefully it's helpful to others, Africa, PanAm, or otherwise.
Loved:
* WARN Powerplant. I know it gets a lot of ******** from people, but wow was it a great choice. The truck that replaced the FJC has separate winch and compressor units, but for something you're using only occasionally (except during the wet season) this was fantastic.
* Spices bought from Whole Foods before we left London. I read a study in the first year of my Ph.D. that a friend, who was an anthropologist from Oxford, had passed along to me at a pub. It said that people don't miss the foods from their cultures as much as they miss the spices and flavors. I certainly found this to be true. My girlfriend and I both love Asian food (from Hong Kong originally) and having the right spices was a godsend.
* Wifi router. Huge luxury to be able to be away from our "home" compound for a week or two and be able to divvy up a 3G connection between friends in camp or between a laptop, iPhone, and Kindle easily. Must-have vehicle upgrade, in my view.
* Field surgery kit. I managed to get a drill bit buried pretty deep in my finger after only a few weeks in the field. My girlfriend (the medic, thankfully) expertly extracted it and it healed well. The outcome using local (non-sterile, awful) tools would have been very unpretty.
* Hydrocodone and epinepherine. Honestly, these are the key two items from a pharmaceutical standpoint. We carry autoinjector (epipen) epinepherine and a bottle or two of vicodin. Obviously Cipro (for serious intestinal issues or to prevent infection after a serious wound) and Malarone (which just came off patent and is much cheaper now than when we packed for this trip) are important to have, as well.
* Nikka single malt. Wonderful stuff. Not going to start a whisky debate, but bring your favorite. That having been said, there is a Chinese merchant on the edge of Gulu who imports decent stuff and will even have a 750ml of Maker's Mark in the back occasionally - the days of having to bring whisky from the UK to Africa are over; I'm sure the same is true in SA.
* CCI .22LR MiniMag (plus your favorite stuff in appropriate caliber for whatever other weapons you have aboard). Wonderful ammo. Feeds in nearly any weapon, from a .22 pistol to older rifles. Useful for a million things, including putting a sick goat out of its misery on the roadside.
* Kuhl pants. I'd been a devotee of Prana and North Face and most of my pants for travel had always been Prana. I bought two pairs of Kuhl pants and had my tailor take a crack at them before we left (I find it hard to find pants with smaller than a 30" waist). Fantastic product. I have two pairs of the Revolvr model, and they held up to all kinds of abuse.
* Good batteries. This is a key flaw of the iPhone and iPad, you have to carry a spare device if you want a spare - you can't carry backup batteries. To me, it's a fatal flaw. Carry good, fresh batteries for whatever devices are important to you. One extra per device per six months is our rule of thumb.
* BIG inverter. I had a big 1200 watt power inverter in the back of the FJ, which saw a ton of use - and not just outside the compound. When the grid was down in town, it was nice to run a device (or charge a laptop) in the back of the truck.
* Good knives and two or three good pots and pans. There's nothing worse than preparing food or slaughtering a chicken or cutting a fish with a poor knife. We brought our best knives and that was ABSOLUTELY the right decision. Two or three good pots and pans are an excellent use of weight, particularly if they nest in one another.
* DEET (already mentioned in posts above) - dilute it for your washing and put together one more toxic bucket each month for your bed net and other items.
* Books. Huge compromise here, as books weigh a lot and you could fit 30,000 of them in your Kindle. But carrying a few of the right ones can turn around a gloomy, crappy day and make it productive or thoughtful. Huge advantage there.
* Good hand tools. Impossible to come by in the developing world (I've seen a hammer snap in half). They key ones are two adjustable spanners, a ratcheting multi-head screwdriver, and a proper set of sockets. To add to that, needlenose pliers and basic electrician kit is enormously useful.
* Tarpoulin and shower curtain. Bring two of each. Hard to find anything waterproof in Africa that isn't torn, destroyed, smelly, or whatever. Awesome to have fresh ones. Thin gauge and take care of it is better than thick and heavy. The girlfriend loved the shower curtain for privacy in a lot of situations. Applicable to travel nearly anywhere, in my opinion.
* Graphite lube. Get some at your local high-end bike shop or find it online. All lubricants available in Africa are foul, sticky, and gooey. It isn't the 1950's anymore, there are great lubricants available. Bring along some Loctite for when you desire the opposite effect - things like adhesives and lubricants are NOT widely available in the developing world, in my experience.
* Really good drill. Get a really good drill, the kind a builder might have in the box of his Hilux for years. You may feel that you won't need it, but it's striking how often this one tool made life immensely easier. Buy bits meant for specific jobs, not the kind that are coated with unobtainium and claim they can do anything. They'll last longer and your expectations and ego are less likely to be bruised.
* Boots that fit well. Find a pair that fits well out of the box. Break them in, but make sure you could run a 5k in them if needed. Now buy a second pair. Break that pair in. Bring both. This is what we did and it was one of the best decisions of the pre-trip packing/planning.
Hated:
* I brought an extra of every cord and cable we carried. Good idea in theory, but actually cheap Chinese USB cables are available even in the most remote parts of Congo, Sudan, Rwanda, Ethiopia, Somaliland, etc. Stupid to have carried this stuff, in retrospect.
* Small camera cards. I finally gave up and bought a pair of 32GB CF cards. This is a stupid place to economise. Buy the biggest cards your camera and budget will accept; using power in camp to download stuff to your laptop because your camera is full is a bad use of electricity and time.
* Axe. If I knew how often I'd be doing axe work, especially beheading chickens in bulk, I'd have brought a better tool. Again, stupid place to save money. Thankfully, I had a big Chinese butchers cleaver that I'd bought years ago at Stanley Market in Hong Kong. It did very well with some crude boning and slaughtering tasks and made quick work of guinea fowl and other common roadside purchases. Great for jackfruit, as well.
* Inferior sand ladders. Our original plan had not included much travel north of the Ugandan border and certainly no travel north of Juba. As our plans and obligations evolved, we ended up encountering more sand and loose silt (the red, awful stuff that is slick as graphite but sticks to everything during the dry season) than we'd ever planned. I guess I should have gotten the Maxtrax (now thinking of buying Maxtrax version 2).
Wasted:
* Toiletries. We took too much in terms of toiletries. Overall, I would say things like lotion and sunscreen (things you have on your body often) are worth having the XYZ brand of. I feel pretty strongly about this stuff, so I'm not going to have some random crap when I can have my Alba Kona Coffee after sun lotion (learned when I lived on Curacao for a year that this stuff is worth its weight in gold after a day in the sun). But we ended up giving away a lot of our stuff to friends at the end. Overall, probably close to three kilos wasted on personal care stuff due to overpacking (and, likely, over-rationing).
* T-shirts. Every site visit, meeting, etc. seemed to lead to the obligatory free T-shirt with the name of a bank, NGO, local political candidate, or some other nonsense on it. We ended up giving them all away at the end, but it was a waste for these T-shirts to be transported to Africa in the first place (not a single one was made locally).
* Oil. I did oil changes preventatively and frequently. In retrospect, this was a mistake. The oil was very clean the first time I changed it, and this should have been a message to me. In fact, the best thing you can do, in my opinion, with a modern Toyota, is not to do a single fluids change while in country (unless you're in a clean service bay). You're probably introducing more crap into the engine by doing a fluids change. Probably better to run it for 15,000 miles with Mobil 1 than to change every 5,000 and risk contaminating the system with the billions of nasty little bits flying around in the air. I didn't have an issue, but I will do this differently next time.
* Took too many clothes and like the 80 Series post above took too many fuel and water cans. We had two 20L water cans and could have only used one. We had four 20L gas cans and this was crazy overkill relative to any of the distances between stations we encountered, even in remote areas like Somaliland or Sudan or the tripoint region in Uganda.
* Warm clothes. Took too many. Could have gotten by with one hoodie. Short-sleeved officers shirts (the bush sort you see UK surplus) and good pants are all that was needed, plus some t-shirts as well.
Agree with Dave on not washing the truck. Our FJ got washed in Baltimore, America and then didn't get washed again for over two years. In fact, I think that spray-down in Baltimore prior to shipping is still its most recent car wash (I know the subsequent owner and it's unlikely he's washed it...). Believe me, in a few months your truck will be so covered in red African mud and dust that you'll blend right in.
By the way, that "over-rationing" part is a serious problem and something that's hit me on my last three major trips. You have to just realize that you brought a particular amount of X supply to last Y days and it's okay that there's only one package/gallon/can/whatever left of it, because that's how you planned it. I hear this from other friends who plan large deployments of people and resources. We're all so afraid to run out that we don't use what we have. I'm trying to get better about this, but still have not improved much.
