You need to have rules, rules and rules. That way you can make classes, classes and more classes. Then you can order trophy's, trophy's and more trophy's.
That way everyone goes home a winner, winner and winner and everyone is happy, happy, happy.
That's La La land though and I would suggest you not expect a perfect first event and some will aid you for your second event by discussing more rules, rules and rules for more trophy's, trophy's, trophy's because there is always a need for more classes, classes, classes so there is more winner's, winner's, winner's and more people can be happy, happy, happy.
Any chance you could have a semi-stock (up to $648 of bolt on to the left side only stuff), every second paddle cut by 18%, black in color only, between 1703 and 1932 miles old, no warranty left, rider weight between 241 and 244lb, age between 56 and 60 class??
This happens everyday anyway. Everyone goes out into groups and the race changes to what's in your mind at the time while your out having fun. Trouble is who will believe the results if you post it on the internet without the trophy's to prove it.