I would like to offer this as an experiment for haunters.
If you know that you will be filming on day X use that information to help with advertising (before you use the footage for advertising). For instance, let the radio know you will film on day X. Tell them the scariest place in town will be filming for TV (or live TV to make it sound better).
This is like running an ad for extras in a movie. People come from all over to do that!
So, as an experiment, I would like to know the results. It could boost popularity before the shoot and after. Plus those people who show, will search for their appearance during the commercial online later only to forward it to their friends and family.