[JRTJH]

Looking at it from a slightly different perspective:

1. If you turn the battery disconnect off, you will NOT be charging the batteries, but the batteries will be connected to the trailer In-Command, the LPG detector and possibly the CO and Fire/Smoke detectors, so you WILL be discharging the batteries, ending up with "completely discharged" (and damaged batteries) within a couple of weeks, even with the trailer connected to shore power. The only "end run way to prevent this" is to completely disconnect the batteries from the trailer electrical system. DO NOT rely on the OEM battery disconnect system, you'll likely not achieve "complete disconnection" and will end up with discharged batteries during the storage season.

2. You have a "highly sophisticated" battery charger/trickle charger built into the trailer. It's the WFCO power center. It is "at least as good as any trickle charger you can buy to use in your garage, and is better than most of the low priced systems like the ones from Harbor Freight or Tractor Supply or Auto Zone" to keep the batteries charged.

3. Removing the batteries to store in your garage or basement will potentially increase the chances of an explosion/fire in your house or the outbuilding where you store them. If you choose this method, make sure you have adequate ventilation around the batteries to dissipate the "off gassing" that will occur.

So, with a "designed specifically for the purpose battery maintenance charger" already installed in your trailer (WFCO power center) and the potential for issues with removing the batteries (including damage to the trailer/blown fuses when you reinstall them), as well as the possibility of increased risk while in storage in your home, why risk all the disadvantages.

If the trailer is stored where there is shore power available, just leave the batteries in the trailer with the battery disconnect in the "connected" position and monitor the battery electrolyte level monthly.

Also, remember to check the shore power cord regularly to make sure that the trailer "really is still connected and the power center has power". Essentially, that is the same thing you'd have to do if the batteries were stored in the garage: That the trickle charger is connected and working and the battery electrolyte level is correct.