It will be impossible.  The Bay area has extensive experience dealing with the fact that real estate prices are astronomical.  You are not going to be able to do what you want to do.  You would be wasting your money buying a RV and trying.  There just flat are not any low cost options and "stealth camping" will be recognized and dealt with quickly.  
There is a reason wages are sky high in that area, and it isn't just because they want to hire the best and the brightest.  Unless you have highly desirable tech skills or are a management star, you will likely find you can take a substantial cut in pay and live in a more affordable area and have a much higher overall standard of living.