There are 2 handy attachment points for a trickle charger on the rt side of the engine so you don't need access to the chassis batts. Hopefully they pointed that out in your walkthrough. If you are in a very cold climate, besides running at least once per month, I would put on a trickle charger.
Also, if you aren't aware, there is a plug in near the chassis batts for engine heater.
2015 Jayco Seneca 36 FK
2016 Jeep Wrangler Unlimited tow
2010 Tiffin RED 36 QSA - gone
2011 Monaco Monarch class A - gone