Working on the interior. I got the back seat to fold flat by “deboning” the bottom cushion, That is removing the cover and sewing a piece carpet on the bottom, and a little stuffing in the bolster edges. I cut a piece of stiff foam to protect the fuel pump wires. The seat belts hold the cushion in place. It’s not uncomfortable, a lot like the jump seats in the back of old 911’s, just a lot more head room. While I was at it I’ve been sticking sound deadening every where. I used this stuff- MP Global Products QW100B1LT-I put it everywhere there is a flat spot, Using 3M spray cement. Turns out the FatMat .80 is cheaper than two layers of the Home Depot stuff. https://www.fatmat.com Carpet from Rock Auto turned out ok, needed some pushing- pulling and gluing.
Might want to add in a thin layer of high density closed cell foam to improve back seat comfort without losing the flat layout you want. John
When I started this I thought about carving the seat foam, or padding it out some how. Then, I came to the realization that, I don’t ride back there, I just want it to look good. Cheers, JC