These trailers are very much like
fiberglass boats. Made in a mold with a Gel coat sprayed in first, followed by chopped glass and resin. The Gel coat is typiclly thicker than standard
paint, meaning you can often take a skim coat off the find like new coating below. You do this a few different ways. The easiest is to get a buffer like this:
7 in. 10 Amp Variable Speed Polisher
and some heavy buffing compound made for machines and get to it. You will be amazed how well this works. My 1988 chalked
scamp looks amazing compared to when I bought it. It's work, but not rocket science. Follow it by a good coat of UV wax, and keep it covered if you can. The reason its chalky is because the outer couple of mils of gelcoat (the part the buffer removes) has been ruined by the sun.
As for those rust spots, try the buffer first. If the compund and wheel action don't quickly remove it, hand rub is with 320 wet dry sandpaper, being careful to go slow and not dig below the gel coat. If you do, they make plenty of stickers (mine has a Buffalo Sabres Logo strategically placed where there was a ding) that can cover it up.
Take Care,
Steve