I've never cleaned the roof of my fifth wheel, fearing I'd likely do more damage than good. I can see that a clean white roof might resist sunlight more effectively, but other than that, what is the ...
It's a commercial roof material that isn't ever meant to be washed. The more one washes it the more the protective white layer wears down. OTOH, some roofs are very visible and I can see why some would want to clean them from time to time.