do you pay per machine or per rider? - like I have 3 dirt bikes, but want to bring 5 friends and take turns riding. do i have to pay for all 5 or just 3?

Per rider i believe

Per vehicle

you pay per vehicle, an all day "dirt track" pass is $20 per vehicle, but that's the only fee I know.

You pay per bike.

You just pay per vehicle that you are going to ride so just three

For the dirt track I do believe you paid per Rider