Best way to level when the jacks don't work

I've alway's used and carry with me 2"X10" Douglas Fir wood planks 24" in length. I get my wood at Lowes (I buy one 2" X 10" X 8' long) and they cut it for me for free. The 10" planks are wide enough so all of my RV Tire is on the board.

Doesn't matter if it's a million dollar motor home or a $100 used pop-up, the principle is the same. Use a carpenter's square and put blocks under the wheels.

I have found the best place to find "level" is on the door frame with a carpenter's level. Hold it vertical against the frame, and use the horizontal bubble. Turn it 90 degrees and the other direction.

Of course with a motor home, you don't have the advantage of cranking the tongue up or down. But still, tires on board or blocks, or Lynx blocks... it's the only way.

Obviously the best thing to do is ask the park owner when you check in for a level site so that any leveling done will be minimal.
If you use the leveling blocks be sure they contact the entire tire tread on both of the duals.

2X6 blocks about 12 inches long. Cheap and effective.