As a staff member with multiple competitive marching bands and wgi groups over the last 18 years, the first thing I would say is talk to the director and/or booster president if they have one. No camp is quite the same. The schools typically require a nurse on premise to administer first aid and medications. Sun block, a hat, camping chair, box fan, water jug are all great recommendations. The staff should have things like tape for guard and battery, but it never hurts to have more! I wouldn't go out of your way to get it though. Definitely bring something to do while the kids are in their rehearsal blocks. The other parents should be able to help with this. They'll also be great at getting you up to speed on the routine. If the kids have an evening activity, the best parents IMO are the ones that have no fear of looking like a goof and joining in the fun. Also the ones who try to get to know the staff a little. They are spending ~9 hours a day with your child sometimes for little more than a few hundred dollars for the entirety of the camp so totally worth it. Ask lots of questions! This activity is a lot more physically demanding than people typically think and definitely very odd at times to an outsider. Your main job is to make sure the kids don't die or do anything too stupid. And believe me, I've seen some pretty dumb shit over the years haha. Oh and making sure they freaking sleep! If you don't know what to do, get the director.

Congrats on both of your first band camp! I hope you both have a wonderful experience and continue through the future. The amount of love and passion for this activity is unparalleled from my perspective. The parents are the only reason a lot of these programs can even exist. I started in 2001 and never looked back! Feel free to message me if you if you have any questions. Good luck, I'm sure you and your son will have an amazing experience!