Assuming you find the point to insert your switch (likely at the back and bottom of the fridge - open the lower vent panel and find where the 12v enters), I would run wires from there to place your actual switch inside the trailer. I would put it in some location that is not going to accidentally switched off, but is still fairly easy to access from inside.
And yes, like said above, it does require 12v to run, but if you want it totally off that is not an issue.
Just the 2 of us in a...
2015 Freedom Express 246RKS
2002 GMC Sierra 1500