Just a question or two. How would you comply with the 500' from persons or property regulation? Would the Feds consider it a "congested area" because of the kids and other people, and hold you to the 1000' regulation? Remember, it's not how YOU define the regulations, it's how the Feds define them that counts in any enforcement action against you. I'm not trying to pee on your party, I'm just trying to get you to consider all the possible problems and get the proper permission before hand to keep you and everyone else safe and violation free. One more thing, a good friend of mine died some years ago doing almost the same thing in a J-3 Cub. He was dropping ping pong balls for a city event in Montana, the balls were marked for prizes for the kids. Something happened, engine failure or he stalled it and hit a tennis court and was killed. Thank God no one else was injured. The impact didn't even seem that severe from the video. One of those TV shows that play "Shocking accidents" used to play it once in a while. I'm just saying to think every possible problem through beforehand and get the proper permission from the Feds so nothing bad happens.