I have a friend who was a band director in Alaska for 3 years before he moved back to the states in the early 2000's. I asked if he had heard of them and he actually had. It was just a group he had heard of in passing.
He is not a drum corps or marching band person at all. After I described the activity to him he laughed and said that they might benefit from the SUN NEVER GOING DOWN in the summer for a time - holy s###! He said that people draw all their shades to make some assemblance of night.
Again - not a confirmed sighting. Maybe they're a parade corps or something?