Isnt the lack of Cat II and III at BZN more to do with RF protection zones outside the wire?
Now I (thankfully) know very little about the technical side of ILS ground installations etc, but this comment was in my mind as we landed on 09L at LHR last night. RF protections outside the wire......the M25 is at 1 mile final on 09L (well, and the 09R but we rarely land on the right) with an industrial estate at about 2 miles, Windsor at 4 miles etc etc.....another 'hering rouge'?
And to answer the other question, the fog has gone - but due back tonight - so the problem goes away again. Maybe all the hot air cleared it up....