Don't think you need to worry about winterizing in Bear Valley winter.
I had several motorhomes on snow, including cheap Toyota ClassC and never had freezing problems.
We don't have negative temperatures and if that happen, I doubt you will think about going in the first place.
When you have heat on inside the coach, it makes "air bubble" around that keeps even exterior siding warmer than the air few feet away.
Than black tank seem to be resistant to pretty low temperatures and if you have gray water tank just hanging under the coach, you can dump a gallon of antifreeze in it.
I drove to Bear Valley only once years ago, but I80 and I50 summits make for +- 20 miles of snow driving during storm and again, that doesn't happen very often, although we hope for wet El Nino this winter.
