Al, I would allow my daughter to go. Sounds like she is ready for something like this. You have taught her well and at some point you will need to cross this bridge as a parent. To help relieve some of your concerns you might consider asking the school about their chaperone selection and vetting process. Are the chaperones teachers, parents? What are the sleeping arrangements etc. Ask the questions you need to ask and if the answers are not to your satisfaction maybe this is not the first trip she should solo.
Pat