Welcome to Class C! I went back to "View Posts" and it seems you did a lot of shopping and settled on this Sunseeker... Decent choice... the FR Class C line is really gaining popularity here.
If you had the coach winterized and parked it with fresh engine and generator oil and stabilized gasoline (and ran the generator to get that fuel into it!) then...
1. I don't understand why you haven't just taken both batteries inside for storage and occasional trickle charge.
2. Running the road engine without driving (or generator without a heavy load like a couple electric space heaters) doesn't benefit anything.
3. Unless your converter/charger is just off the chain voltage-wise it won't boil your batteries in that cold weather.
4. If you choose to leave the coach plugged in, get a little trickle charger and connect to your chassis battery. Or two of 'em and put one to each battery after you disconnect their negative terminals from the house and chassis.
I'm suspecting you may just not want to be lugging two or three heavy batteries from RV/storage to the house and back...
