Jim,
You are getting some great suggestions here.
As you can see, the forum members are generally divided into two distinctly different camps.
- Some suggest keeping it cold inside.
- Some suggest keeping it warm inside (I am in this camp).
There is no right or wrong here, it just boils down to what you want out of the experience (a tent vs. a motel).
One thing though that I suspect all forum members will agree on however is that boondocking in the Fall and Winter really hammers batteries.
- It takes more power to keep warm (if you are in that camp).
- During the longer nights, most folks are in their units more and the lights are on longer.
- Batteries don't have as many amp-hrs. available when they are cold.
All this leads to depleted batteries. And regularly depleting batteries below about 50% will shorten their useful lifespan.
So you are correct in focusing your efforts on batteries and charging methods.
So you may want to consider is a method of measuring (or monitoring) your battery capacity real time. A simple plug-in voltmeter, used correctly, can give you a rough idea (don't let the voltage drop below about 12.3 to 12.2 volts). Or you could install a bit more sophisticated battery monitor such as
this (or similar by other companies). Either way, you need to keep a close eye on your batteries or you will wind up sitting in cold and dark, and eventually with less money in your wallet.
Fall, winter, and spring is our favorite time of year to use our trailer. So the effort it takes to make it happen (in comfort IMO) makes it totally worth it.
Hope you enjoy winters peace and quiet,
Steve