Refrigerators of the 70's and 80's where required to be somewhat close to level to keep working properly. Much research has gone into the refrigerators, and by the 90's the condenser was working much better, and they are now able to be much more 'off level' and still work great.
The big concern is the ammonia and water mixture staying in the evaporator, and not returning to the boiler, the boiler overheating and running dry, and any remaining ammonia in the boiler turning back to a powder that will clog the orifices. Just driving around with the refrigerator off will normally get everything working properly if that where to happen. Manufactures will allow the units to run something like 3 degrees off level these days. That would be really uncomfortable to try sleeping in a bed leaning that far side to side or front to back.
Like said above the stabilizer jacks will keep the RV from rocking. However they are strong enough to pick up about 1,500 pounds with ease, so they can lift the trailer side to side, even if that is not their intended use. Most of the leveling side to side should be down with ramps or blocks.
Good luck
Fred.
