I keep going back and forth on this topic, but what I always end up with is this: I used the TT winter, spring and now summer since I've owned it. I have plans to use it for the fall and again in the winter and spring (it doesn't snow much around here, so camping year round isn't a problem if you don't mind rain).
If I were to cover the trailer, I'd bet dollars to doughnuts that when I wanted to take it out for the weekend the cover would be wet, and then I'd have no place to lay it out to dry, so it would end up full of mildew.
So I guess no cover for me (though I will get covers for the AC and tires).
2012 RAM 2500 Megacab Laramie Diesel
2016 Jayco Eagle 284BHBE
ProPride 3P WDH