I have no experience with your area but it sounds like you are on the right track. Ventilation is a main key in reducing mold. We get high humidity only in the Summer months in my area but I expect coastal South Carolina has a much longer season with mold inducing humidity. While bleach is a sure fire way to kill mold it just isn't practical on fabrics in a camper .... unless you want all the fabric to be white.
Here is a site I found a long time ago with some less damaging ideas.
3 Ways to Kill Mold Naturally | Care2 Healthy Living