This is surprisingly effective, but only if the players keep changing.
If it is always the same activists showing up pretty soon they will get tuned out. "Oh not that guy again..."
But if there is a rotation of several seemingly disassociated people, across the country, then it begins to look like the movement that it is.
So get out there. Don't let your public servants control the content and contexts of the interfacing they have with the public they are supposed to be serving. Take a risk and speak up, even if it's not your turn, and particularly when it is obvious that the meeting is being purposely controlled to avoid substance.
Let's not let our inclination to be polite enable tyranny to continue unchallenged.