I would also like to know the distance...
I would also like to know the distance (width) in inches from the dividers to the outside walls.
I don't know that but I do know that ours (again, the 8-person) fit a queen size air mattress on each side. The inside "wall" does angle a bit if your mattress is too wide (nice option actually) so if you have a super high mattress, it may be a bit awkward. Not sure. Ours was an "all terrain" Aerobed which I think was about 9 or 10" high and it was fine.