First, let me say thanks to LandCruiserSteve and Silverdusk for the ideas!
I followed their lead and built this box and platform. It works in several configurations. The box by itself with the back seats in. The box and a sleeping platform when the back seat bottoms are removed, and then a third configuration that is flipped forward for a full flat platform, when the front seats are moved forward. I got a Cabela's delux camp bed.
Cabela's Deluxe Camp Bed - 48x78x3
and trimmed the sides of it to fit between the back sections. It is better than an air mattress for us because it is lower, we have more space, and it is very comfortable. (plus we don't have to inflate it). It flips down on the front when the front seats are back, and then when we stop and move the front seats forward it flips up for total coverage.
Thanks again LandcruiserSteve and Silverdusk!
