This sounds like a great opportunity, Chadwick !
Considering that you are dealing with Girl Scouts, you
should probably
get some preliminary lessons into the girls heads before they even get to the camp by contacting their troop leaders or scout masters or whatever their hierarchy calls it; sorry I is ignorant here.
We gotta inoculate the youth with better choices that don't exclude fun! That's the front to fight.....I think....
Send them a simple rocket stove design like
http://www.thedoityourselfworld.com/DIY-Rocket-Stove-Make-Your-Own.php and get the little girl troopers to get a feel for it first hand at a scout meeting, and maybe bring it home to camp with them.
...Giving them ownership of it in a way and eliminate the need for longevity, if they were bringing their own.
You could also, if time was permitting, get the campers to help with the cobbing of a
rocket mass heater bench. The bones of the whole system could be ready, and you could quickly assemble all the parts, while explaining it, and get them to cob it up, and then demonstrate it over the
course of their camping stay, and invite them to ask questions, and get them to give suggestions on making it better, and thus owning the idea in their imaginations.
Inspire them. And they will inspire you.
Each camping group coming at a specific time could take part in building a bench, and as such would have a lasting memory of it, and pride in the accomplishment. New troop members would be told about it before they got to go to the camp, and would want to build one too. Maybe other
permaculture projects could be dreamed up for future camping years.