I suspect you are going to have a real fun time on your first trip to a campground. That will be a pretty bright light burning all night long...
My scare lights which are on both sides of my fifth wheel on the rear sides has a control switch near the full size picture window on the rear wall of the trailer. It is not near the entrance door access. Mine is also not labeled - Just a switch on the wall...
This always 'ON' light will also run down your battery real quick as well if you are running without shore power connected. I would look all around the living area for an unmarked switch.
I actually find it hard to believe it is always on. It would not last sitting over night when on when parked anywhere. This light should run from 12VDC which gets it power from the trailer battery. When plugged into shore power the on-board converter/charger keeps the battery charged up... I'm suspecting your battery is either dead or not hooked up and the scare light only comes on when you are plugged into shore power ???
Roy Ken