Our camper canvas has been attached by means of snaps attached to a 3/4" thick piece of high-density polyethylene screwed to the cabin roof. But the stress of the curvature and exposure to the elements had caused it to crack in several places. So I found a place that would sell me a similarly-sized piece of Starboard and fabricated it to match the original. Then I took an old board and cut it to the curve of the cabin roof and put the Starboard in the sauna as I was heating it up today. I checked it at 140F and it was already approaching wet noodle stage. So I quickly clamped it to my board and now have a perfect, stress-relieved replacement. And I get a nice steam-bath to boot!
Al
Al