Just saying, I think it'd be great if every big group had some of the following.....

Documentation.

Go-Pro camera, always on. Be great if it had wide angles. High definition cameras to take pics of license plates. Highbeam lights.

Communication.

Airhorns to signal in case of trouble. Stormwhistles are another alternative. Speakers to organize. Mounted speakers would be great.

Protection.

Edit - come to think of it, this may hamper the look of the movement more than it helps. Removed two items. Umbrellas. Sunglasses. Anything to douse fIam e..... F ireblankets. Extinguishers. Anything for the elements, including heat. Fans to ward away potential fu mes.

Hopefully, people won't have to use a single one of the above, but if you keep your bases covered, it could make a difference.