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 ...
I got Lazy and I went one year without washing my roof and what happens is that you get Nasty white Chalk all over your Front cap when it rains and stains it so then you have to Scrub it off with compound and re-wax it NOT FUN! I will never let that happen again