We do not currently own a MH, but are in the market. We have rented class C's in the past from Cruise America. When we rented, they would tell us to try and park as level as possible, or the fridge mi...
I had used a 2-d bubble level for a number of years, and keep it in the freezer to check. Lately I've been using a Stanley bubble level app on my smartphone (free download). The bubble level app shows a numerical readout in degrees so can verify that the fridge 6 degrees front to back and 3 degrees side to side limit is not exceeded. Usually am <2 degrees either direction, greater than 2 degrees is not comfortable anyway.