George, I have an AF1150 and previously a 990. During short term storage I haven’t had an issue with freezing pipes at the temps you describe; however, if possible I’d certainly run a small heater and fan as you described and open the cabinets and the cabover step just to be on the safe side.
Have you given thought to draining your cold and hot water lines and running your water pump dry. Those conditions you described shouldn’t cause problems with the massive amount of water in your fresh water tank or the hot water heater. Course the hot water heater can be easily drained and bypassed. I winterize my TC by draining the water lines, running the water pump dry and blowing air at no more than 30psi thru the city water access with the water faucets open.