Ouch!
Well, an oxidized surface will generally create a pretty good bond. Oxidation yields a similar result as sanding.
If paint scrapes off easily it’s likely due to lack of cleaning prep.
That said, trying to sand it off would not be advised. In order to sand it effectively you have to sand it flat and you’d inevitably cut into or through some of the original thin gel coat on the filon trying to get all the “new” paint off. This would even be somewhere between difficult and impossible to not have happen even if it was smooth sheetmetal like on an auto.
I’d start with testing several methods, knowing that the gel underneath is relatively impervious to most solvents and that minor scratches can be sanded and polished out. And you’d be cutting and polishing the whole thing anyway if you successfully remove the **** you’re trying to remove.
Prolly don’t know what it was painted with but you can hope it is something cheap and not so solvent resistant since the POs so thoughtfully painted it with paint brushes…
Id first test increasingly strong solvents to see if you find something that will soften/melt the paint. Lacquer thinner, toluene, acetone, paint recucer, mek. Roughly in that order from weaker to stronger. But verify.
If you can do some careful scraping of the areas not bonded well (heat helps too, careful application of a heat gun or propane torch) you might get a good portion of it off by mechanical means only. Note gel coat will withstand a decent amount of heat but goes from good to burnt yellow pretty quick. So you need to have the right touch.
With any luck it’s some old latex house paint and heat should peel it.
If they actually used some decent automotive type paint, you have a bigger chore.
If you do a bunch of testing and find out it’s not plausible then I think vinyl wrap is a great option. Remove whatever can be scraped off. Feather sand around those areas, flat sand any nasty brush marks and you’re ready for a wrap.
Wrap will telegraph any imperfections though.
But you can save the graphics if you’re good with laying down pinstripe tape. You can outline the graphics in knifeless tape just like you would around the windows and such. And wrap isn’t too hard to do on flat surfaces.
Good luck!
