Well there are 2 ways to go about it.... one you could clean the hell out of it and if you choose this way you will want to make the cladding extremely nice which could take you hours.

The second way would be to find a truck with a winch and go get your VX absolutely covered in mud.... you may not win but you would have the "coolest" car in the show. Just make sure you get a spot dead center of the show so they know your muddy VX is in it.