It is not uncommon for the disconnect not to be a true disconnect. My Tiffin had 2-12v disconnects and neither did a complete disconnect. Sorry had three switches third on the engine did turn off the coach batteries. I asked why they did not disconnect but was told to take the negative lead off, go figure...Ian
I don't even remove my cables in the winter. About every 30 days I go to the rv and start the generator and let it run for about 30 minutes. I've never had the Redwood's batteries go down from sitting.
I keep my trailer ready to go because we have used it in the winter and because I count on it for emergencies like power failures. I do winterize it but I've done that a couple of times a year if I need the trailer during the winter.