OP, you really only leaving AZ for 4 months? And you have power at the storage?
Disconnect batts from camper, hook to tender, come back to fully charged batteries. No need to monitor water for a few months of no use and a smart charger/tender. Or a cheap solar charger.
Your biggest issue is the rest of the camper. I'll have to presume this is the first time you're storing something in AZ (new camper, newbie questions). If you do not have covered storage, your camper will be sun baked/oxidized/rotten tires/etc within a few short years. Make sure you have covered storage. Or, for 4 months only, you "might" get 2 seasons out of a soft cover before it's destroyed, but likely only 1.