The Hosser writes:

My first question is what would be recomended as the "suitable
material"? I went to Garelicks web site and of course they have a 1
inch extension shim. I was thinking of using a industrial grade
polymer cutting board and stacking 2 1 inch sheets cut to a little
over the mounts footprint.

Polyacetal (aka acetal, or Delrin) is stronger. Cutting boards are HDPE, a
weaker type of plastic.