We have a magnetic level (about 6" long, I think) that we put on the drae bar near the propane tank once we get on the site. DH has a pretty good eye, and can tell which board(s) he needs to use to get us level. He selects and places---I just tell him when he's centered on the leveling blocks. Although probably a little more time and energy consuming than the levelers you buy, the leftover boards are free. This has worked fine for us.