Rain, Leak, Dicor but... what happening in walls?

Invest in a de-humidifier. Get a good one. We place ours in the shower so that it can drain into the shower drain, and we leave the grey tank valve open to drain out of the camper. Our fiver is parked on dirt so no problem with the drainage there. We didn't want to keep emptying the dehumidifier's collection tank, or risk forgetting and have it overflow into the camper, causing more problems. Had that happen once.

It'll be almost as good as going to Arizona.