Have not read all of the previous posts, just wanted to contribute a little here.
I have BatteryTenders on my tractor, motorcycle and the car I keep in the garage, they are always connected and charging when the vehicles are not in use. I have 7 years on the car and 8 on the MC and 11 on the tractor batteries.
Since the regular mode of the IOTA DLS-55 is to trickle charge there is the element of losing water due to charge boil, best not to leave it on a stock house charger. I am installing an IQ4 (smart charger add on from IOTA) on the DLS-55 converter/charger for the house battery and I intend to leave that plugged into shore power same as the others. Since I am new to RVing I'm not sure if the DLS-55 charges the chassis battery when the vehicle is not running, so unsure of that for the moment.
Other info, I just purchased a BatteryMINDer 1510 because it has a desulfate step that BatteryTenders do not.