Congratulations on the 2010 Magna. Our rule is it isn't true until you post a pic so we can drool over it
I am no expert on the Magna's but my Allure with Aqua Hot has a heat exchanger in the wet bay that provides some heat to the holding tanks, the water pump and the water connections/filter. Perhaps the Magna has additional exchangers in other basement areas but not sure that is an issue unless you plan to store items in those areas that would be damaged by cold.
The Aqua Hot has both electric and diesel burner capabilities. Your Magna probably has the larger AH unit with two electric elements so you can leave one or both of those on, set your T-stats to a low temp, and that should take care of it. There should be an adjustable T-stat in the wet bay. I suspect you would need at least a 30 amp service to run both of the elements.
I have the small Aqua Hot with only one electric element. My coach is outside and connected to a 50 amp service. I left both my electric element and the diesel burner on and set my T-stats to 48 F last winter and all was well. I did put a 100 watt trouble light in the wet bay near the water pump and used one of those T-stat controlled outlets to turn that on when it got really cold. We had some single digit nights and everything was fine.
Parked inside and if you can use both of your electric elements, you should be fine. Or, you could do a full winterization and not worry. However, make sure you follow the instructions to pump RV antifreeze through the Aqua Hot unit to protect it.