It's cramped before 6'2".
I read about this on one of these threads a while back and wanted to try it out. So on my last trip after driving all day I tried this setup rather than blowing up my air mattress and using my sleeping platform. Big NOPE on this for me.
No where to put legs, lumps in all the wrong places. Found it could make a good lounger by sitting in the back seat and putting legs across the back of the front seat. IE: for evac'ing someone with a busted leg. But after driving highways and trails for 8 hours the last thing I want to do is sleep sitting up.
Back to my sleeping platform for me! It's flat and other than the lack of headroom comfortable.
With the sleeping platform designed right you can get nearly 7' of sleeping room in a 4th Gen. I have just over 6' with my drivers seat still in driving position. (all the way down and back). You'll need to slide the seat fwd and fold it all the way fwd, then build your platform to go over the folded up 2nd row seat bottoms. In my setup (based on the Adv Index plans) The drawers take up the rear and I have 2 platforms that go from supports on the front of the drawer box, and over the rear seats. If you stick with the Adv. Index plans the box will be a bit lower offering more headroom but a slight incline from the front of the box to top edge of the seat bottoms and back of front seat. (mine is taller and so more flat.)
Boort