I learned a good bit from this thread. I had pretty much ruled out canvas as I paddle strictly fresh water, so rot is a big issue. Sounds like polyester has an edge but I have more research to do for sure.

Let me toss out a crazy idea here for suggestions. I mentioned this before but I am SERIOUSLY thinking about building a kayak trailer and I am was thinking about at least partially enclosing it. A Skin on Frame trailer Still trying to work out the details on the design. But I like the idea for several reason. Not the least that it could be a rolling billboard.

I am thinking (without much research) that the Aircraft nylon is a better application for the trailer. Depending on the shape heat shrink might be a good choice too. The fact I can paint it is a plus too.

As for the kayaks, obviously have some some more reading to do.