Don't forget balloons as targets too!

I agree you have a dilemna. As the saying goes, a good deed never goes unpunished. My recomendation is as follows:

1) The proficiency test explained above. 3 Shots in a pie plate at 75-100 yards. With one do over for the fails.

2) The kids provide targets from a recent outing at the range that shows proficiency. Make them aware well in advance or offer a place to shoot on the property sometime before the season starts.

I would make a steadfast rule being no Automatics period. I would limit the number of cartridges to 5 per animal with the adult in charge to follow up a wounded animal. I would also not allow anything over a 30-06(recoil wise) and would encourage 30-30 and 243 shooters.