Battery/shore power question

I treat my 5er as a camper. And to me that means it is used only when we go camping, about 30 days a year. When sitting there at the side of the house, waiting for the call to go and see the world, it is unplugged, frig off, and the batteries disconnected. I will check those batteries throughout the winter to make sure they stay fully charged. I may plug the rig in a couple of times a winter and also connect the batteries for about 24 hours each time to charge them up. That's it. My current Trojan T-105's were purchased in 2008.