If it is a fun show, a driving gaming class is always fun, a safe alternative to to having many people in the ring at one time.
If you go with a traditional class and you will have multiple drivers in the ring at one time, of different experience levels, use it as a schooling approach and ask for drivers to meet ringside or in the center of the ring with their horses and carts before the class actually is in "go" mode.someone can give them a basic rundown, like watching for the cue to cut across when getting too close to another driver and what the class will cosist of.....approx so many times at a walk, a trot, working trot, reversal, center of the ring, backing on judges command, stay approx x distance from other drivers at all time.....
I know it is not the coordinator of the shows responsability to do this, however, if you are having multiple drivers of varying ages and experience in the ring at one time, it is a great chance to educate individuals and makes for a better experience. Many mistakes are made, not because individuals are rude, but rather because they do not know otherwise.