At the risk of being a little too "goth"... this would probably repel mud pretty well.
http://www.phazeclothing.com/product...tal-gloss-kilt


This one might fit the "feel" of the event a little better. Much more Roman Conquerer and less vampire-y: http://www.phazeclothing.com/product...-pvc-mens-kilt

Either way, you're sure to stand out from the rest of the crowd doing the event in a SportKilt!