Wow. That is a piece of work. I'm almost embarrassed to show mine, after something that polished!
I wanted to be able to leave middle seat in (but folded down), and leave the bed/drawer in place when I needed the middle bench. So I came up with a folding design, which allows me to leave it all in the truck...
I also wanted my head at the front, so I could lie on my bed and look out through the cavernous sunroof...And I wanted it to be a half unit so I could pack tall stuff low on the floor. Only needed to be a single, since my dog is small, and my wife will be along when we have the trailer behind us...
Anyways, here's mine (just did it yesterday, so there are finishing touches yet to add)
Battery compartment for a third battery, inverter, etc, in front of the drawer:
If I have rear passengers, its just a matter of flip-flip, and the front half of the bed flips back on itself, and is still usable as a storage surface and drawer.
BTW, vehicle is 93 Mitsubishi Pajero (like the US Montero, except I have a JDM diesel that I imported from Japan)
(looks a little different than this now)