Nice benefit about "Boondockerswelcome" is you can easily a 41 ft fifth wheel in/out, many have water and power and you can stay 1 - 2 weeks. We joined Harvesthosts but after checking most of the sites in California there are very few sites where we can pull a 41 ft fifth wheel in/out of, no water and electricity and limited 1 night (some say 2).
https://www.boondockerswelcome.com/
https://harvesthosts.com/