Jim,
RV's can be used, comfortably, in colder climates. However, I suggest that you ease into it. And, of course, fall is the perfect time to go out and make practice runs.
There are quite a few modifications you can (and most likely will want to) make to your trailer, but only experience will tell you how comfortable you can be in your existing trailer. And your desired camping style and comfort level will dictate much of this. Read through the many threads on this subject for ideas on what others have done. And if you any receive hints from Pianotuna, I suggest you heed his advice as he lives this lifestyle full time in Canada.
In response to your original question about keeping your battery charged: I suggest you double your battery capacity and get a good charger (around 60 amps) that can charge your batteries quickly. Otherwise your large generator will run needlessly and most stock converters just aren't up to the task. Of course, if you do this, you will also likely need to increase the wire size between the batteries and charger to reduce voltage drop.
BTW. During a camping trip last winter when it got to about -18 F, we were quite comfortable in our trailer. We never even used the generator as we had good sun on the solar panels most of the time ...... after I scraped the snow off. However, being able to do this in comfort and without freeze ups took many modifications over a period of several years. "Practice makes perfect" (well, getting closer to perfect anyway....)
p.s.; Don't forget to bring a shovel and chains for the trailer.
Have fun,
Steve