Registration instructions used to say that both captain and stoker have to register. I can’t find that now.
I did find this, though;
“Trail-a-bikes and bike trailers for children under 5 are allowed on the ride. Infants traveling in a trailer need not be registered, but a child riding a trail-a-bike does need to register. Make sure your child wears a helmet. Please note that the SAG vehicles do not carry child seats, so any youth young enough to require a child seat cannot be picked up by a SAG vehicle.”

Us audio techs claim the ability to only count to two . . . because on three the other stagehands lift.