Bring along about a dozen 2x8 cutoffs and place them accordingly more at the low point, none at the high point. Drive or back up on to them and you're done.
IMO if you have to level up more than 3or 4 boards (6") then either live with it for the night or find a flatter spot.
And fwiw I never get too critical with leveling. Not building a house, just parking the house there for a bit. I prefer, if not level, to leave the head of the bed high vs low. Something about sleeping with feet higher than head seems weird to me, unless I'm hammered then I don't care! Lol