GEL Coat options on new to us camper

I noticed this as well, after the detailing was done there was some chaulky white residue on the concrete. He claimed that was the paint and it wouldn't do that if the gel coat was still there... I figured that could be from the roof tho running off onto the sides. Thing was probably never washed up there before.

If I go to cut and polish, what goes on after to protect it? Any car sealant work or something rv specific?

Thanks all