1. I will sign whatever in January and I might even put it on my calendar but that doesn't mean I will prioritize camp over vacation etc.
2. When you start asking me and my child to already give up a huge amount of time, (HS band is NOT MS band) plus asking me for marching fees, etc. when you pile on ultimatums, (punishments), then I start to lose interest in a hurry. And if I, the adult lose interest what do you think happens to the kid?
We have to think differently to get our kids in band. And yes, I know sports does what sports does and that's fine. But sports also motivates their kids better, (we should learn from that).
So rather than going after it from a punitive view go at it from a positive view. Preach daily the importance of camp and the activity, (trophies are not importance factors fyi). Preach daily the importance of MUSIC, not marching band. If you teach your kids to love music you will teach them to tolerate the work parts that they don't like. 10% of your kids not there means 90% were there! That's pretty dang good 3 weeks before their summer really ends. Remember, you are paid to be there, they aren't! Trick them into wanting to be there and you are already doing that with 90% of them. Keep working but as a parent, telling me in January changes little for my August plans. What worked best for me eons ago was having the section leaders calling the kids in June and then again in July. When the kids took ownership the battle was won because peer pressure is as good as it is bad depending on how it's used.