Tim/Jon
How about we use the calendar function to post warnings about large class field trips?
If somebody's really concerned, they can check the schedule and see if there's supposed to be any big groups at the crags they're heading to. I know this wouldn't work for all climbs, but it could work for class field trips from the Seattle Mountaineers, Everett Mountaineers, WAC, UWCC, Bolps, SAR... and any class with a dozen people or more.
Just a thought.