I also scoot around in my spot and try to get as level as possible but when that fails I have
4 Of These to get level, that is usually all I need. 2 for the rear duals and one each for the front if needed.
I used to carry wood like the others have said but found it to be to heavy and cumbersome. These are light and easy to store. I also carry a set of
These, a gift, but have yet to need them.
I also use
One of These to get fore and aft level as well as side to side level. I put it on the floor of the freezer to check how level it is. Works like a charm.