I follow the Monaco/Beaver instructions we got at purchase.
Pretty much I start with Dawn or a clear coat/paint-safe auto wash, working of course roof down. The wrong products can do more harm than good to clear coat and fiberglass, so steer clear of strong detergents. Simple Green is good for tough spots if need-be, but use only Extreme Simple Green for Motorsports on hard to rinse aluminum like a radiator. You can use a power washer, but beware what it can do to sealants and through-roof fittings. Use caution scrubbing such things as AC housings, whose finish oxidizes and disintegrates under much solar impact. Coat such plastic things with Aerospace 303 protectant.
After thorough cleaning, I use Mequiar's liquid cream wax (M66 I think) and my Porter-Cable 7424 polisher top to bottom. It takes awhile, but after applying with the polisher in 3' X 3' sections, it's an easy microfiber wipe off. Just watch the slickness on the roof... I wear boat shoes up there.
Admittedly I haven't done this all as often as originally intended, sometimes due to "laziness", sometimes due to illness. The coach really glows when I've managed to do the job, and the roof stayed clean and oxidant-free for a year thanks to the UV protection. The more exposed upper clear coat suffered, though, from my more recent negligence. So if you have the wherewithal and time, do it at least once a year. The rig will wash easier next time too, if you can make the waxing an annual thing. It's far easier with family help, a luxury I've only been able to muster once. Reckon I scared em all off after that experience 😂.
Joel