How do you level when needed

I use the lego blocks for mny years. But then my rig is light. As previously suggested lumber is good call cut to size. Cement stepping stones work but are heavy

I use Andersen Camper Leveler. Happy with them and they have no damage after 4 years of use on all surfaces.

We used to carry some long boards - worked OK but a nuisance for sure.
We sure liked the automatic levellers when we switched to a Class A - really missed them when our C came without - so we are back to carrying boards.

Do a google search - this has been discussed many times.

Pieces of 2x8 or 2x10

If they are not pressure treated, they can double as firewood.

If you can find a source for scraps, they are free!