score:3
For either Tahoe or Yosemite, you could get caught in a snowstorm with relatively little warning, that might require chains or even closure of the road. Both are about 4 hours from San Francisco, so you are adding an entire day of driving. I would suggest neither, and instead going either to the Wine Country north of San Francisco (Napa and Sonoma valleys, also Point Reyes National Seashore), or San Diego. Highway 1 is two days. And it is not easy to drive in an RV.