I use composite door shims as well to eliminate the dreaded platform rattle. However this won't deal with the issue of the pressure waves put on the platform, it will just transfer it from the brackets attached to the platform (in the form of wearing through the 1/4" holes) to the brackets on the transom which is a much bigger fix. I just hope that Moomba through-bolted the transom brackets with a nice thick metal plate backing....