To cover or not to cover, that is the question.
Obviously, all RV's are made to be in the weather, but IMHO, covering one & protecting it from the elements as much possible is the best thing to do, long term. :B
I use a heavy silver tarp purchased from Harbor Freight for $45. This is my third season using it & I know it will last a few more. Securing a cover PROPERLY is the key. :S
Another thing, For TT's up to 24' I have a simple process to put on and take off. Two people, 15 minutes, no getting on the roof & no ladder. :h