Over the years I have taken out my TT batteries and hooked them to a trickle charger in my garage during each winter. I now have the TT under covered storage at a local storage yard which has electric...
I would disconnect the batteries and take them to my house. I can set them on a shelf and put a trickle charge on them sometimes. Less chance of them walking off that way. ALSO... Make sure every door and Hatch is locked. Don't leave anything in you storage unit or camper that might be stolen. Wouldn't hurt to put a shackle on your trailers hitch too.