If you will post in the signature line your RV information that will help responders give better information. I carry a variety of boards to first get the trailer level side to side, then when dropping the landing gear use appropriate stacks to get that level also. I try not to extend the legs too far to improve stability. These procedures apply for me regardless if I have a leveling system or regular manual legs.
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2020 Ram Laramie 3500 DRW CC 4WD Diesel