It would help to know where in the bay area you'll work or want to park the rig. The options are limited.
First short time visitors can op for south of San Jose or Petaluma or Pacifica. Candle Stick park is an option and $$$. Pacificia may be $$, but call about rates. South San Francisco has 1 maybe 2 trailer parks that might work for you and there may be one in San Carlos. Fairgrounds in Alameda county. The fairground in San Jose looks rather marginal and there is/was a trailer park just to the south. There is a county park in Half Moon bay and a private park. I don't keep keep up with the above status, cost and security.
Search for trailer parks and see what you can find.