There are a quite a few issues that would need some looking into.
1) Permission from local Police and/or CFO.
2) Permission/Permit from Municipal authorities for use of roads and/or parks.
3) Volunteers from Veterans Legions and perhaps even local military and reserve units.
4) Sponsors for all the up front cost.
5) Medical units dictated by a large gathering of people.
6) Settling on a decent date for all involved.
If it can be treated it as a moving gunshow……

It just might be possible.
Shoots and gunshows are public events.
I wonder how much those trigger locks are going to rub?
I like the idea of a run/walk. That way it could be a family event.