Quick answer: A backpack sign works well at events where people move along a known path and your message needs to travel with them. It's not a fix for missing permits, missing directions, or a weak offer.
Map out how people walk
Find where people enter, wait, gather, and leave. The moving sign should meet people at a point where they can act, not just wander around.
Write for someone walking
Use one clear event name or offer and one action word. Small print and long details need a spot where people can safely stop and read. Don't count on that everywhere.
Work with the event
We agree on the area, hours, staff contact, weather plan, breaks, and any venue rules before the sign enters the crowd.
Track the event window
Use a named offer, headcount, booth question, or another simple signal. Be honest about what that signal can and can't prove.