Have just finished prepping for a try again. Have found towels easier to work with than plastic, helps get stuff off the shoes, are reusable and if you find on sale are likely cheaper too. Walmart, Target, Kohls etc. Then screwed halves of an astroturf like outdoor (read cheap here too) door mat to the running boards to scrape shoes on. Also similar on tailgate to trailer and at the side door to help keep from tracking into the trailer. And plan to use one when getting in the racer to try minimize salt inside it as well. Whole thing can be done for $20-25 including the tape if you shop it right.