Okay, actually if your Arctic Fox is like many, most, other trailers, even when there's nothing turned on there's still stuff running and draining the battery. The CO detector, propane detector, and other stuff. The battery should still be charged by the solar panel with the battery disconnect switch turned to OFF. Do that first thing and see how the battery holds up. The next step would be a manual disconnect switch on the negative battery terminal.
In our Fuzion, even the radio was on when the battery disconnect switch was turned OFF. We installed a manual disconnect on the negative terminal, which it sounds like you need to do. I have a clamp on amp meter to see how much my battery is drawn down with the battery disconnect switch turned to OFF.
Howard and Peggy
"Don't Panic"