I have seen the future of our free Soapbox Engage Check-in app for Salesforce ... and it includes a custom field set with all the custom fields you'd like! Event teams will be very, very, happy!

You can get the app for free (without the new feature above...for now) on the AppExchange: https://appexchange.salesforce.com/appxListingDetail?listingId=a0N3A00000FtRrlUAF