Do you happen to be an Elk member? If so there are Elk lodges with RV parking that have limits on stay, but during the winter might be negotiable...$18-$25/night. Fremont Ca, Tracy, Gilroy, Sonoma to name a few.
Alemeda County fairgrounds in Pleasonton Ca, French Camp RV park in Manteca has monthly rates, Garlic Farm in Gilroy. Probably others but those come to mind.
2008 Jeep Sahara '4Dr"