The most important point is: how cold are the temps dropping to and for how long?
The heat system will bring on the gas when the mode is set to electric because at about 40 degrees heat pump efficiency is gone. In fact the roof units can actually ice up when it is cold so there is no sense trying to run them.
The heat pumps will not protect the water/utility bays...you must have gas heat to keep that area above freezing. And if the temp is below 10 for an extended amount of time even the gas heat may not help. We had to put a reg. 60 watt bulb down there to keep the pump from freezing. If you aren't dealing with temps that cold you don't have much to worry about.
Propane supply is of course limited in any RV. If you will need propane heat for more than a week...you may need to find a way to refill the onboard tank or have additional propane tanks available.
Let us know at what temps the rig is sitting in and for how much longer you will need to maintain the rig. Folks here can help walk you through steps to prep for more extreme weather.