Today, I went out and re-covered with the old sheet. It went way better than I expected. TB, rolled on full strength a foot at a time, the canvas rolled onto a long dowel and unrolled over the fresh glue, pressed down by hand, then ironed flat under a hand towel. Advice: do not let the iron slip onto the latex paint, especially if the iron belongs to your wife. She will NOT be happy.
The little "lines" near the middle are where I accidentally hit the paint with the edge of the iron. In the second pic, you can see how flat it glued down. You can see, though, it stretched out nice and flat.
Where I had stored the canvas, it got a little dirty. I'll probably wipe it down with a damp cloth and apply another topcoat. In addition, I'll have to put 3 coats on the parts where there's now bare canvas.
John61CT, I agree, the risk of delamination might be higher. I can't say how much. But, if you can apply PMF over PMF, there is probably no penetration into the first coat either. I can't see where this is greatly different from that. On mine, the glue is soaking into the plywood and is soaking into the canvas.
I can say, part of the original problem was "undergluing" on that part, which didn't adequately seal the plywood, which led to paint getting in a gap, which led to swelling. I didn't make that mistake again!
The back side of the fabric does show some paint flow-through, but not like you'd think. There's lots of "virgin" fabric there to soak up glue. In the end, I think it will be OK.
GPW: I intentionally left my edges long. I'll trim them back to 4-6 inches or so then overlap them onto the other panels once I begin assembly. Reason being, once I begin assembly, I will have to move outside, meaning I need to minimize the time the camper is exposed to the weather before it is sealed up.