I know nothing about Dirty Kanza. Are you sure peanut butter is the right rating? (https://fluentincross.wordpress.com/...fic-mud-index/)

If the mud sticks to your tires in clumps there really isn't a good tire for it, but skinnier is usually better to minimize the build up. If the mud is thick but doesn't cling to your tires, something wide with spiky tread is probably better. The trouble is that it's a pretty slim difference in weather between these two types of mud.

If most of the course is going to be gravel or otherwise hard surfaces with sections of mud in between I'd probably look for a file tread with aggressive side lugs -- something like the Clement LAS or the Kenda Happy Medium.