We are going too, for the first time to this event. Went to the off rodeo in Townsend last year August and couldn't make the 4.5 hour trip twice in the same month.
We where there last week and it was great experience! Our guide was very knowledgeable and taught us to use the individual features rather than the Goat modes, which i personally liked.
There had not been rain for awhile, so it was dusty and not much mud. Agree with using bug spray...