If you want statics, or maybe some demo runs around some cones, then some local teams might come.

If you plan to do any fights, then no one will turn up with their heavyweights - its a case of, if you believe the Heavies are safe enough to just have random fights in the middle of a crowded event space.. then you shouldnt have a heavy.

It used to be done to an extent in hay bale arenas so on. Ive not heard of these kind of events since i started attending (09), and i doubt people would travel to attend that kind of event anymore - testing in a closed off space is different, but not an actual "event"