Presuming you are NOT going to be plugged in during storage:
2 major things to do.... Disconnect the negative battery terminal on both coach and engine batteries! The disconnect switch does not fully remove all use of the coach batteries. With both engine and coach batteries disconnected, the inverter doesn't matter. I use a knife switch on the engine battery and typically just unhook the negative terminal from the coach battery. With your PC, you have 2 coach batteries... Do not disconnect the jumper that goes between the two batteries, disconnect the 2 black cables that come from behind the battery tray.
Second... Fully rinse and drain both sewage tanks, the fresh water tank and Hot Water Heater, and blow out the water lines. Then pour RV antifreeze in the shower drain, bathroom drain and kitchen drain. Use a total of 1 gallon between all 3.
You may want an RV dealer to do the winterization of the tanks and water lines.