I have lived and worked in Oakland for many years. In the last 5 years there has been an EXPLOSION of homelessness, and used RVs are one of the housing solutions people have chosen. And the area around the estuary is one of the places where they congregate.
The good is that you could park on the street and most people would not look askance. The cops will roust you when they get around to it, but just keep moving.
The bad is your little home could be surrounded by squalor (the homeless are just as aquistitive as the rest of us, and less organized) and a class of neighbors you might not care to know, although I do not want to demonize the homeless. Many of us wage slaves are 3 paychecks from homeless ourselves, and that's a common story in the present times, but others live on the street because their demons and addictions keep them from living anywhere else.
My suggestion is to advertise in Craigslist for a driveway to park in. Oakland, Alameda, and the surrounding cities are old fashioned inner ring suburbs, and you could possibly find a driveway or a backyard to park in.
There is ONE RV park in San Francisco near the train station that is full constantly. There is an East Bay Regional Parks District campground (Chabot) that is semi-close, and has hookups, but you're limited on how long you can stay. You could try parking overnight in either some of the outlying lots near the Oakland Airport, or there is a business park on Harbor Bay Island with parking lots. You could try the OTHER end of Alameda, at the old Naval Air Station, which is VERY SLOWLY being redeveloped.
The nearest true GA airport ("North Field" at Oakland, the commercial airport until the late 1960's, is GA, but it's still within the "fence line" of a major international airport) is Hayward, and it's a good 15 miles down the freeway.