Seats in passenger model uncomfortable to sleep on. Any suggestions?

Is there any after market solution for making the seats more flat so they're comfortable to sleep on?

I saw a plywood platform and 2 folding legs that someone made to put a cushion on for kids to sleep on. It made the seat portion wider and flat for the cushion then stowed away while driving. Now that I think about it might have been for the front swiveling seats but the same concept should work.

This summer I just bought our passenger van and to sleep three of us I cut 2 Pieces of 1/2 in plywood 25in x 68in to fit in the passenger seat rows. Cut a piece 22in x 60in to fit over the front seats. I supported them with 2x3 frames. They fit REI 25 inch camp pads perfectly. They worked but they were a pain to put in and take out. We're getting the van converted professionally this winter and will get a front bench platform frame with foldable legs for a permanent solution.

Thinking cheap here, I was thinking about the plywood over the seat and somehow click it into the seat belt latch so that you wouldn't need any additional support. You could possibly move the 2nd 3 seater seat back to the back 4 seater floor slots to make plenty of room between the first and second seat to make it easier to get in and out of "bed".

Yea, as I said, thinking cheap here...

stew