"My rig is a 2017 Newmar Ventana LE.
My understanding was that if I needed to run ANYTHING - i.e., my lights, tv, clock radio, microwave display - that the inverter needed to be "on"... the fridge does run on propane when not plugged into shore power, as does the WH."
You first need to identify which things are 120v and which are 12v. Also note the fridge and some other things that have temperature controls, need 12v to run the controls even when the appliance is on 120v. The 12v things will work even with no inverter (which is just another 12v thing)
Next identify which 120v things are on inverter. Your microwave and clock are for sure as noted in the OP. The fridge will stay on 120v unless you force it to be on propane if any 120v is available. The WH is on 120v or propane by manually switching.
You have a transfer switch between shore power and generator, but also one in the inverter so it will power things with no shore power or gen supply. Not everything will operate from the inverter (air conditioner won't) but the fridge and WH could well be wired to do so, and that would run the batteries down quickly as described in the OP.
I gather the power has been turned off in parts of your area due to the fires, so you need to learn how your rig works. Hope you are in a safe spot.
