Anne & Bob,
Sorry to hear of your troubles, but you have learned it is best to disconnect the ground cable on the starting battery while in storage. So welcome to the "I Killed My Battery Doing Nothing" club.
You might want to consider carrying extended length jumper cables to bridge between your coach and starter batteries. Or do what I do and carry a 4/10/20/40 amp battery charger and extension cord that will run off the generator.
FWIW, my 2007 E350 chassis starting battery seems to drain down every-other month like yours did, but 5 years running, and all is still well after that mishap. Hey, it's better than my Corvette which will drain down after 4 to 5 weeks.