Rv roof maintenance ?

Not sure but you should check out the new fad with the Bedliner spray. They say it works good for leaks and such.

What about the Galvanized trailer roofs? Do those need to be repainted periodically?

I think the rubber roofs need to be retreated with a wash/revitalize cleaner every 6 months

Try cleaning it with spic-n-span the powder version and a plastic bristle brush. You may have to scrub it twice and treat with dicor roof guard when dry. If the EPDM roof material itself seems compromised there is a 10 year warranty on the roof material. The caulking/sealant is on you.