Consider working with the event organizer to incentivize them to promote the event at your location.  We suggest offering to donate 10% of any dinner sales during the event where the patron has written the name of the event on their check when they pay.  This way you are only paying on the increase in sales that the event brings into your business.

These are sales that are above and beyond the sales that you would normally do on a normal night that day of the week. This ten percent is much less than what it would have cost you to advertised and marketed the event, which they are doing for you for free. Also,

1. It is a way to acknowledge to the event organizers that they will be rewarded if they go the extra mile to have all of their 18 bartenders consistently promoting the event and your venue (which can generate tens of thousands of social media views, plus your logo on a multitude of promotional vehicles) that you will donate ten percent of the increase in sales

2. It accommodates people who for whatever reason may not want to participate in the bar area but would still like to contribute

3. Your image as a business is greatly enhanced for a very small amount- only 10% of the increase in sales in the dining room only - don't include bar sales.