Here is an item you should considerUltra TRIK-L-START Starting Battery Charger/Maintainer
It is called a TrikLstart
It came standard on later model Winnies. I installed one on mine and thats why I am also able to maintain my chassis batteries.
The wiring diagram it shows for Winnies, you must have your ON/OFF disconnect switch on, however a simple wire change on the battery isolator solonoid and it will work with your switch OFF.
This is a must if you do not have supplemental 110 AC available when in storage.
You also must have sunshine, In the winter during prolonged periods of bad weather I have watched TV for a couple hours while running the genny and I do just fine with the set up I mentioned inn my previous post.
Most of the complaints are about maintaining chassis batteries, not the house batteries.