Hey Scott,
You are welcome to check the Wheelchair Accessible Van for Expeditions anytime you want to get an idea of how 4 captains chairs, and a sofa would work.
I have a removeable seat and made a wheeled base plate to ease getting it in & out...of course in your setup it would stay in all the time.
Sportsmobile.com has a done of pre-laid out designs on there...I used the EB-71 as a starting point.
There is also a do-it-yourself tool that lets you play like it is paper furniture that you can move around.
For a family the extra space of a EB is a must, get a pop top for the sleeping space upstairs and enjoy the heck out of it