While CA State Parks are way too expensive and sorta funky, San Diego County has a network of 9 parks.  These typically are in the foothills, one of them is out in the desert.  They are comparatively cheap.  All of them are very nice.  Clean, well managed, delightful actually.  They used to be super cheap....but inflation of course has taken it's toll.  Still....as a local....I highly recommend.  And I use them all regularly.  A nice thing:  Electrical hookups....so little electric heater in Winter to take off the chill; most of the year, temperatures are just right.  And most have easy cellphone access.  Lots of wildlife wandering through.  Again, highly recommended.....any of them.