The first weekend in October, you can camp at several California campgrounds for $50 for the weekend, according to RV Daily Report. You can see the list of participating campgrounds there. That's a pretty good deal for private campgrounds.
That same weekend is National Public Lands Day on Sept. 29. In some places it does include camping, but for the most part, it means free admissions to national parks and forests. The National Park Service, U.S. Fish and Wildlife Service, U.S. Forest Service and the Bureau of Land Management are all participating. You can more information and links at the Public Lands Day site.
RVers should take advantage of these days to visit public lands if possible or stay in a California RV park. Jaimie Hall Bruzenak