Double cover for boat?

Since I can't find any reasonably priced inside storage around here I was thinking of throwing a large, white breathable RV type cover over it while it sits outside. It would have it's regular trailerable cover on underneath. Any downside to doing this? Just trying to keep my gelcoat reasonable over the next few years

Thanks

Bakes

down side is mold
you have to kept the two covers seperated from each other ( air cap )
Go to Costco and just get a 10 by 20 car port cover
then all sides are covered
another option is to have side panels made that attach to the cover and the trailer ( evolution I believe makes them)
my .02

I did that exact same thing for two years without any problems using a regular 40'x20' tarp over my sunbrella cover. Never put it away wet and make sure there's air flow, facing into the prevailing winds helps that happen. As long as there's circulation it doesn't matter if they touch. Of course i don't have high humidity so that helps.

put damprid in the boat if your really worried about mold

It really depends on where your at & what the weather is like there. We did this with the MC in Seattle & got mold between the two covers, even with the Dri-Z-air dehumidifiers inside the boat. But here in eastern WA, it's usually so dry, it's hard to find mold growing anywhere. Even when it does rain, it's usually done in a day or two & then dries out again.

If the extra cover makes you happy & feel like your taking care of your baby, so be it. Whatever works. I'd like a carport myself. Or better yet, a boathouse.