I leave mine in the trailer disconnected with the disconnect switch. It goes down poast -30 here and never an issue. Once or twice during the winter on a nice day I will hookup my big intelli charger and top the battery off which only takes an hour or so as batteries does not lose much charge at all when disconnected. I use the exact same battery on my 30 mile electric fencer and it goes for 2 months at a time without being charged sitting in a wood box on an old plastic milk carton and never has an issue.
John & Deb
2011 F250 Lariat FX4 Crew Cab 6.2
2011 Flagstaff V-Lite 30WRLS
Days Camped 2013: 16 2014: 5 2015: 3