I have/had a 2001 Casita that was so chalky and oxidized you got powder on you if you brushed against it, plus it had mold and streaks. Yuk.
I scrubbed it with Barkeepers Friend using a blue scrubby pad...wow, it came out sparkling but dull...
PolyGlo was the miracle maker, I applied three coats using a piece of microfiber towel that I dampened beforehand. The coats dry very quickly so by the time I finished one round I could just continue around again. I did four coats altogether, so over a few days my Casita looked like new. Two years have passed and it still sparkles. I will probably give it a good wash, I use regular car wash soap, and do one more coat before the summer.
I also refreshed the black paint
on the bumper and hitch..it looks like new!