An outside compartment holds all my leveling blocks, chocks, jack base, WD pipe and the battery powered drill w 3/4" socket for lowering the stabilizers. A little Hoppy surface level (available
everywhere) sits in there where it won't get smashed. I set it on the tongue in front of the jack when I'm setting up at a site. I can quickly determine right-to-left level, set up leveling blocks as I'm moving the trailer, and then level with the tongue jack when I'm unhitched -- that one location is easily visible during the entire process. A friend went so far as to tack his down in that location with some caulk when he had a tube open for other purposes. You get a real good sense of how far the bubble is off to the side and whether that means one or two blocks under wheels on one side. You don't have to get it perfect -- within half a bubble is very comfortable and okay for the fridge.
I haven't driven away with it sitting there yet.

But they're under $3 if I do...