You may be too tall to sleep in the S if you want to stretch out full length — I find that I rarely do that. I do use my
air mattress a bit diagonally; it is about six feet long when inflated, so perhaps too short for you. The picture of how I arrange it is in post number 4 above.
As for the bump left when the seats are folded down, I use a folded up bedspread to level that gap. It is quite comfortable and I can't feel the drop off at all. Although the front of the air mattress extends a bit over the end of the folded seat, it is rigid enough to support my head and pillow.
If you are going to try to sleep two, one of them your six feet two inches, on some sort of double air bed, then I think you may have difficulty fitting in the back of the S unless you are willing to curl up a bit. I've heard of a double bed being fitted into the back of an S but haven't seen any pictures. The back is a bit narrow — I measure it at about 41 inches (104 cm) wide and 76 inches (193 cm) long, about 12 inches (30 cm) of that unsupported, as you say. If you use a mattress that is not stiff enough, as mine is, to support your head over that gap, you could try a small piece of plywood to provide some extra support; it wouldn't have to be very long since your weight would keep it in place on the folded seats. If using an air mattress, however, I think it should be stiff enough to not need support since the weight of your shoulders will be firmly over the folded seat. (This assumes sleeping head forward; I would find the hatch too low for comfort — too confining — if trying to sleep head to the rear.)
FWIW.