My experience has been that while covers protect from some calamities, they also contribute to others. I now get it deep detailed/waxed annually, and in-door storage, if I can find a place that falls within my price range. No matter what, it gets the annual deep cleaning, detailing & wax job, most RV businesses provide this service. While costly, in the long run it is not that much more than the covers (which do not last that many seasons anyway).
I use this on my vehicles, and have used their products on RVs before:
www.zymol.com/
I haven't tried McKee's RV wax & care products yet, but they do make good auto protective products.
www.autogeek.net/mckees-rv-detailing-products.html
