We camped Christmas week just up the road from home in our National Forest at the 5600 foot level and had 55 degree day time and 42 night time temps. The wind, though, made it a bit uncomfortable outside. So other than for for walking the mutts off and on the time was mostly spent reading all week long. And we were the only rig there most of the time with over 100 spaces available, maybe 2 or 3 others would come and go for a day or two.) Total cost: Camping $70, fuel $28, Nighttime propane maybe $20 as a wild guess.
California is a wonderful state to travel in with a wide variety of different things to see and to. Unfortunately a large segment of the RV population seem to get an upset stomach at just the thought of crossing into California.
About the only thing that would keep us out of another state would be open warfare.