Until you get your battery disconnect switch: (Assuming you have not completely killed the battery.) Charge it up and just unhook the negative cable when the camper isn’t going to be connected to shore power for days or weeks.
(Somebody may say disconnect the positive side - not sure it matters electrically speaking).
I’ve been “getting to” installing a disconnect switch since 2013 and making due with pulling the negative cable until then...
When the camper won’t be used for long periods I pull the battery out, take it home, and keep it on a tender in my Garage.
So far it’s worked for me. Still on the battery that came with my trailer when new in 2013.