How about a draw play, but very delayed. Have the QB drop back and wait a few seconds. The D will think it's definitely a passing play, then hand the ball off to a back and hit the huge holes that should be there. Call 2 passing plays before this one to make them think you're airing it out.
I'm sure at that age, the defenders aren't going to be able to watch for the run while going back in pass coverage, to their minds, it's either pass or run and they'll make up their mind and commit to one...then you do the other.
