Specs for Absorbtion refrigerators safe operation is up to three degrees off side to side, and six degrees front to back. This is pretty substantial off level, as far as comfort goes. If you use your wheelbase specs and the three degrees, you can figure how much your front ( or rear ) can be higher than the opposite end. (Assuming fridge is mounted with its sides facing forward and backward.). Simple Trigonometry. In my short RV with a 156” wheel base, one wheel can be 8” higher than the other and still be safe for the fridge.