[JRTJH]

If you want to "protect something" from condensation, freezing rain, water intrusion, you'd probably be money ahead by focusing on the "A frame electrical stuff". Between the 7 pin umbilical connector wired into a galvanized box full of holes, the break away connector wired with crimp on connectors, those "not water resistant" 12 VDC mini-breakers and ground cables "screwed into the front bulkhead (behind the propane tanks), there's enough "built to fail" electrical wiring that's ripe for corrosion and failure to keep you busy for days.....

When that's done, crawl under your trailer, look at the wheelwells. If they're covered with DARCO (cheap plastic tarp) you're "ripe for floor rot"....

Spend your money on things that will make a difference in trailer longevity. A "high tech canvas cover" isn't really a part of that loop......