You're are going to get different opinions. We've never covered any of ours over the years without any damage. I've seen repeatedly over the years covered fivers, trailers & MH in the storage yard. Most don't make it through the winters here. They tear at the corners, and anywhere there is something sticking out like awnings, gutters, etc. I have seen were they rub on the paint and gel coat.
My wife and I notice the new units that cover theirs. We take bets on if they will make it through the winter. She's more optimistic, me not so much. Some here will tell you they have one and have never had problems. All I'm saying is we've never purchased a cover based off our experience in seeing the results first hand.
Best bet - put it inside a cover garage.