IMHO a huge measure of success is if the traders want to come back next year. If the traders come both aviation and food, then it is likely that the people will come. Likewise if the people come, then it is likely that the traders will as well.
As for location, it is a flyin. So long as there is enough hard bed accommodation for those who want it then where it is shouldn't really matter. For those who do not want to fly in then it needs to be near enough to and RPT airport with suitable accommodation/car hire. I think Narromine in association with Dubbo just about covers that. As I say just my opinion but the one time I landed at Narromine, I thought it was a beautiful little town and lets face it the people in the country could do with some of our dollars.