Since the power jacks on my Class A are... Not working up to specification (They do work, just not up to spec) I built a set of stair steps..
These are 2 by tire width planks.. I phrase it that way because your tires may be a different size than mine.
1 Foot
Two Feet long
And finally three feet.
I put the "Small" end up behind the tire and back on to them, I use two of them on the rear.
I also built some 2-step (just the bottom two slabs) so I can level front to back and side to side. THey work great
THey will NOT work if you have close spaced dual axles though.