I hate getting that dirt on the carpet in my boat too even though it is a fishing boat. What I do is keep my crawlers in my live bait well where I have a water supply. This keeps them out of the sun. I also bring along something like a cool whip container or larger and fill it up with water and leave it in the livewell too. I then put about a half a dozen crawlers in the water which cleans them and allows them to take on water and plump out. It saves the carpet and keeps the hands cleaner too. I just change the water regularly which keeps them cooler and cleaner. As someone else said on this site, keeping them in water doesn't hurt them at all.