Event wise, there are many ways it can be construed and by the FAA side of thing they would emphasize the most restriction. I would tell you this, make sure you plan out your flights and do not fly over crowds.
Personally I would say use good judgment and as you fly constantly take in account if something happened with you aircraft where it was to drop out of the sky, what would it drop on. For a polo event, I have discussion with US polo and have been interview by a few news outlets on the international level on how to use the technology in the sport.
Because the field is so large and the majority of the crowd is focused on one side, at certain events the sport allows for a fairly safe environment.