Yeah, there doesn't seem to be any one other than Mantec that have actuallyade them.
From what I can tell in the pictures, it actually doesn't sit lower than the top of the rear windows and sort of tucks up in there. The opening starts around the hand grabs and goes to the first roof support(?). It also looks like it easily comes out so you can put adults in the third row.
I have some left over 0,8 gal from my tool box, might get a guy to fold a prototype up and see how it works.

