Slab City. It's rough and tumble but it is free.
If you have a car - er, mobile apartment - your problem is largely solved. Park in industrial areas, they get a lot fewer cops. MAKE SURE YOUR TAGS ARE UP TO DATE.
If you have an RV, you can park in WalMart parking lots for up to a week at a time.
Good luck, been there - without a car, no less. Sucked but I survived.