[Carl n Susan]

Earlier posts in this Topic touch on all your questions. But to summarize.
If you are on shore power all thee time, then leave the battery in the unit. The onboard converter is better than your trickle charger. Be sure to have the Battery Disconnect switch so that the key can't be puled out. That indicates 12V is passing from the converter to the batteries.

If you are determined to remove the batteries, not a prospect I look forward to with 4 or 6 batteries, you can do so. The battery cables will be disconnected which obviates the need to play with the red disconnect key.

The disconnect in the front compartment is solely used to disconnect the 12V power to the dedicated inverter which supplies your residential refrigerator. The disconnect in the convenience center disconnects the 12V power to MOST (not all) of the 12V devices. Notable exceptions include the hydraulic system and the propane detector. Pic #1 is the battery disconnect for the inverter and residential refer.

Without shore power, you can leave your batteries in the unit all winter. They need to be fully charged and the cables disconnect to avoid parasitic draws. They will be still charged in the Spring.