Hi,
My buddy was in Yosemite many years ago in February. When his tanks froze, he drove to Fresno where it was much warmer, and the tanks thawed overnight, and he was able to drain the next day.
Because you will have electric, I would recommend taking a electric heater and not use the Mr Buddy heater ever (something about a high pressure propane tank with a relief valve that will spray out propane next to a hot flame scares the heck out of me).
If you do find the water pump or tank is frozen, then put your electric heater near it for a while.
Is your pump inside? Perhaps under a dinette seat? Or in a storage compartment? If you can put the heater near the pump, it will both warm that area, and keep the tank warmer, so you can take a longer and warmer shower too!
I have dry camped in 19F with no problems, using my Olympic Catalytic heater and some use of the furnace. I have also lived in my RV at 20F overnight in Portland OR for a couple of months in a campground with power, and ran 3 electric heaters to keep everything warm and working.
Good luck,
Fred.