I don't have any helpful advice about the wetting....what I can offer is a thought about GS camp. Contact the director of the camp and explain the situation to her. If this is a council camp, they camp with hundreds of girls a year and your daughter will absolutely NOT be the first/only 7 year-old in this situation. Find out how they teach the counselors to help the scouts like your daughter. There should be a procedure that will let your daughter have a rewarding camp experience while protecting her privacy. It may be as simple as providing a private changing area for all of the girls to use and keeping an opaque trashbag there. Anyway, the director should be able to tell you about it and then addressing the situation with her counselor (ahead of time) should enable your DD to have a great camp experience.

Happy Scouting!
Lenora