How about this one, get Hyper to bring 8 moto bikes to the track each race. Have a “bring a friend to race” moto where kids that race can bring a friend who doesn’t race and they get to use the motobike for they day. Limit each kid to three races on the motobike and they can not have held a license before.
This way they are all on the same prepped bike, no modifications allowed.
You might be able to get Hyper to bring out 2 or 3 of the small versions of the motobikes for the little guys too.
Good advertising for them and the track.