Sure, we can do that too! We will provide you with wristbands, so that it is easy for the bar staff to attribute your guest's purchases to your special event minimum. We will still require you to put up the deposit for the event, but you will likely get a refund depending on your purchases. If staff are not notified about guests' purchases we are not able to track them properly and their sales will not count towards your event minimum, so please explain this to your guests.
You can even do something in between: e.g. give everyone a drink ticket to put their first beer on your tab, and then they are on their own dime. It is up to you! We have drink tickets on hand if you would like to do this.