Just wanted to quickly respond to this- I understand where you are coming from, and that we don't want to put our kids in a bubble, HOWEVER- if, as parents, we weighed our child's reputation in the decisions we make as parents- we are essentially saying that their peers opinions of right/wrong, cool/uncool is a reliable factor... That is exactly the OPPOSITE of what we try to instill in our house. Don't just go along with the flow- make the decisions that are right for you- that support your goals, dreams and beliefs.
OP- it is a tough decision- saying no to your kid is always hard. But you are the parent, and you know your situation best.
As I was reading your post, my gut initially was that I would allow my child to go. Until I got to the part that said that parents who were not the chosen few couldn't go... Here is the deal- You are the MOM- in my belief- I am granted access 24/7 to my children. Period. Dot. End of conversation. No school, doctor, coach, etc is going to tell me or their father when we can or cannot be there. (Assuming you will have completed the school's requirement for a background check ,[for the safety of all kids there] and are willing to pay for your way). It's a tough call, but the minute a school tells me I am not "allowed" to be with my child...game on.
We have only had one incident of this, when our oldest went on a Show Choir field trip overnight to Busch Gardens. I was not a chaperone, but I was the choreographer. When they returned, I went to class the next day to congratulate them, and the principal was talking to the class (there was a behavior issue during the trip with a few kids) Rather than talking to the kids individually, they choose to bring the whole class into the conversation- that is fine, but when I went into the room, and sat in the back the principal told me I couldn't be in there when she was talking to the class... OH REALLY? I have an adult wanting to talk to my daughter in a closed room...NOPE
We went around in circles, my husband came up, etc. Long story short (kindof)- we found out she was actually breaking county protocol, and had to answer to that.
The point is- you are the mom- make your decision based on your gut feeling. Good luck and let us know what you decide!