This applies to N. CA only. I am not familiar with below SF.
Stay near the main roads when on Highway 1. Marin County has extremely aggressive LEO due to the extreme cost of the land. Stop and look, but try not to spend the night. The minimum property value there is 6 figures. There are only two Walmart locations in the north coast Eureka and Crescent City.
Between 1 and 101 do not go off paved roads. Most of the rv parks there are either meth havens, or priced high to keep from being meth havens. Many private landowners have contracts with a paramilitary type private security company, Lear Asset Management. They are extremely well equipped.
http://talkingpointsmemo.com/dc/lear-asset-management-marijuana-raids-mendocino-california
If you want to try to spend the night at turnouts off of highway 1, do so knowing that you will more than likely be woken up, asked for ID, then told to move on tomorrow. Off of highway 5 you will be more likely to find a more friendly attitude towards dwellers.
https://www.google.com/maps/d/viewer?mid=zWUSQ5x4Gi9s.kBKwuXReQ0l8&msa=0
Stick to what is already listed.
I have lived the homework, and cannot give enough warnings. Stay away from going off road in the N CA coastal counties. It is one of the most beautiful places in this country, but stick to the parks and let people know where you are going and when you will be back.