We bought the same coach in July. Just leave it plugged in. Get a battery watering system because it's a pain in the rear to water those batteries each cell at a time ( location). I add water about every three weeks. It takes me about 4 minutes start to finish with the battery watering system.
But keep the refrigerator turned off. It turns on the minute you add power.
Have you been on the roof? Most likely you have a large solar panel up there that keeps batteries charged. If you aren't in covered storage it will keep the batteries topped of as long as you shut off the two switches at the front door and the battery cutoff by the engine in front of the inverter. It's not one of those tiny air conditioner mounted one.