We have the Lippert leveling system, and the first time we used it we were at the dealer, learning all of the ins & outs. Ended up with ALL FOUR tires off the ground by using the auto feature. So we learned the manual -- very easy.
First, make sure you've set your emergency brake. Then turn on the leveling system and hit the "manual" button. It should tell you which corner of your rig is unloved. Hit the directional arrow (N,S,E,W) that is lit until your center light is green. That's all there is to it!
If you don't feel comfortable doing this on your incline, then find somewhere a bit more level and try it there.
However, if you're on that much of an incline, I'd be worried about the forward pressure you'd have on your levelers for long periods of time. As GMC said, getting it level should only be necessary when running the fridge (or putting the slides out).
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