I just found this in the online issue of Motorcyclist. If you have ever read Peter Egan's column in Cycle World he has mentioned the Slimey Crud group. I believe it was a group initially and now it is a rally. Apparently they have one of these in the fall and in the spring. A couple of neat bike pictures in the article.
https://www.motorcyclistonline.com/slimey-crud-motorcycle-cafe-racer-rally-spring-2019/
