I have a 2010 Cougar 276RLS with two 12 volt batteries that will discharge in two or three days if I am running the frig on gas. This is just setting with no other use such as lights, pump, slide etc...
I would bet your fridge is in a slider and it has an electric "12 volt" fan between the upper and lower coils. Those fans run pretty much non stop if it is warm out and will suck a battery down in a hot minute. If you are seeing this supplement with a solar powered coil fan and that should help out a ton