Okay..got a good picture in my head now. Yes, it does have "cross-supports" that run from side to side along the contour of the roof. Do it kind of like a sub floor would be done, then cover it with some shag carpet...lol. (SHAGgin' Wagon). So simple---thanks for the response and guidance! Hardest part may be transitioning the bed area to the cab roof...it looks a little different...the foam board should be easy enough to cut and shape though.