You would probably have the same types of potentially disruptive and expensive repair issues with an older RV as you did with a boat.
I lived in that area some years ago. Many people seek affordable housing in the Bay area, and RV parks located on valuable real estate such as Marin County are not going to be cheap. They also are not likely to welcome any of what the owner or manager might consider seedy-looking older RVs longterm.
If you google RV Park Reviews, Marin Ca, you'll find a couple of choices in Greenbrae near the Larkspur Ferry to the city ($12 round trip daily with Clipper card). Read the parks' numerous rules regarding the age of RVs, etc etc.
With weekly rates, looks like you would need to plan on about $1600 a month for site rental at the Marin RV park in order to get electric, water & sewer hookups, according to their website. (IF they let you stay there.) You also may need to refill your propane tank periodically for cooking, furnace, etc, Add the purchase price for the RV and several thousands more potentially to keep it in workable condition, and it could be cheaper to rent a small apartment.
Government run campgrounds (state or county parks, Federal govt campgrounds) usually have two week stay limitations and often do not provide a full range of services at the site such as a sewer hookup.
