303 Protectant is about as good as it gets when it comes to UV protection, but it can be hard to find and is expensive when you do. Monaco's instructional video recommends washing the whole coach with Dawn dish detergent and using
Meguiar's Quick Detailing Wax with a random orbital polisher. I did that annually except unfortunately last year, so it's been over 2 years and this is the first summer I've seen white streaks after rains.
That said, my brother has been dealing with classic and other cars all his long life, and says no wax, even those with maximum carnauba content, will protect from UV more than a month before it breaks down
. When we got the new coach, he tried his best to get me to immediately have a carport built for it over our home RV pad. I can barely afford the coach, much less a cover for it in addition; so I figured I'd just try to wax it well once a year and that would have to do. My brother's caution aside, my experience has been that the Meguiar's seems to do the job if you use it annually. Even after more than 2 years, I find dirt or bird stains (and the white streaks off the roof) mostly just rinse right off the sides and caps. I still hope to get a coat on it before winter if my health allows.
Don't know why you were told not to wax the roof, other than making it slick to walk on. The roof and front cap take the brunt of what the environment has to dish out, so if any parts need protection, it's them.
