If it's going to be stationery and plugged into electric I would use electric heat, not propane. That way there isn't a "supply" issue. The question then becomes who is paying the electric bill, you or your family? I would think you should be picking up part of the tab for the electric bill anyway. With air conditioning, electric water heater, refrigerator, and other things you will use a fair amount of electricity. Unless your electricity is really expensive or your propane is really cheap it will be more economical to heat with electric.
However, you may need to still run the furnace some in the really cold winter to blow heat down to the tanks and plumbing. Unless, you happen to have electric tank heaters.