1 pc Fiberglass roof vs. "rubber"; "Huck bolted frame?

Rubber roofs (or membrane roofs in general) are immediate turn-offs for me. However, almost all trailers have them unless you go to a place that can make a fiberglass or one piece metal roof. With those, you are not relying on a glob of caulk to keep water out of cracks.

As for huck bolts, I wonder what keeps them from loosening over time. If it can thread on, it can vibrate loose. Maybe put some red Loctite on the threads before putting on the collar and using the tool to mash it down?