CASA don’t need to add any more rules to be able to control fly-ins. All they need to do is show up and pull ramp checks. All in the interest of safety, of course.
Fly-ins will soon cease. Safe skies are empty skies.
If the OP is talking private fly-ins not advertised for public attendance, ensure that at the organisation stage all participants are sworn to secrecy, and said fly-in is on a public holiday. All in the interest of risk management, of course.....