Just watch the weather. I use accuweather with my iPad. If a cold storm's coming, move into the valley. We were staying at the fairgrounds at Mariposa (very basic, but full hook-ups) using it to visit Yosemite about 10 years ago. I was driving my Grand Cherokee in falling snow in Yosemite and driving rain in Maricopa. Awesome! There's a full hook-up campground on a bluff above Lake McClure just off 132 that is very nice. RV Park Northern California | RV Park Sacramento CA | Jackson Rancheria
I haven't been to, but have been told it's one of the best in Cal. 49 is in the foothills. It has a few very steep, short areas and lots of just up and downs. Did it from one end to the other with a 26' Class C in the early '90's. There is a great book, Mountain Grades Directory RV bookstore - the world's largest online RV bookstore
that details such. Last I checked there was not a version compatible with Apple, but my decades old copy is invaluable. No west coast RV'er should be without it.