[Bongle]

I think large beanbags would be an interesting game piece. You could have the bags be of widely varying sizes, and score based on bag mass. The bags could be different colors easily indicating their mass to drivers. Maybe in the middle of the field could be a large walled-off pit that you get bonus points for tossing or dumping the bags into, making an interesting engineering challenge: how do you toss bags consistently?

You'd have to make the bags out of pretty durable material so they didn't spill though. Or have plenty of shop-vacs on hand to clean the field up quickly.