rdcsjc,
First off, before you start adding anything like chargers etc, get to know your rig! What kind of rig is it? What make, engine, trans, how many house batteries, what type, how many chassis batteries, what type?
If you've got manuals for your rig, look them over and see if you can find out the charging system(s) that are built into it or not. There is nothing wrong with leaving it plugged in as long as, any factory "on board" charging systems are a "staged" type. That is, they detect the state of charge of the batteries and then simmer down to a trickle charge or maintenance charge.
But, your manual may state that your coach is NOT to be left plugged in for long periods of storage due to possible battery damage. You'll have to determine what you have or don't have.
Keeping the batteries up, while in storage is the best thing for them, as long as it's not "over charging" them. That way, if and when you visit the coach during the storage period(s), you can fire the beast up, the genny, test all the interior components like water pumps, heaters, and anything else that needs periodic exercise.
Scott