There are a couple of outfitters for hog in Nor Cal. I haven't used them but I've heard good things about them. One that I can remember is called Choppers aka Birds and Boars, and another I've heard about is Tejon Ranch.
Yes, most CA hogging is private land. If you want to try to hunt ranches that are not outfitters, or lease rights on a ranch for a season, you may have to do the homework through the county clerks or whatever to find the property owners and ask permission. One more idea, check with the CA DFG,
www.dfg.ca.gov. They have an in depth report on hunting hogs in CA. I've heard that the hog hunting mecca for CA are private lands along the central coast around Monterey and Carmel.
I'm personally at the mercy of others for hog hunting access, so I can't offer any direct help. I'm alway staying alert for more opportunities though, so if I hear of some I'll let you know.
Good luck!
Toby