Ok, I'm a dummy, composite?mine had the opposite problem so i put 1/4” stock poplar across the entire back row and shims on the sides to make sure every foot had contact
with only 1/16” I’d probably just use composite shims under each foot. The nice thing about the air shims is you can level it perfectly with air shims and then place the composite shims right then. Especially in the front don’t use wood because you’ll spill eventually and it could degrade the shim.
glad you found it useful, I know I was pretty stoked when I found those