S.,
How fun to be a Girls Scout troop leader. I remember our troop leaders working hard and keeping things fun. I do have a couple of suggestions, one I would love to help you with, and others that might work well depending on your meeting space.
1) This is the age that girls start thinking about their appearances and time to get into good habits. I am a beauty consultant with Mary Kay Cosmetics and could teach a skin care class and do mother/daughter make-overs for you. It's been a big hit with a couple of troops my friends have worked with.
2) A cooking class featuring healthy snacks/meal ideas. You might be able to get Central Market (they do cooking classes) to help, they are very community oriented. If your meeting space has a kitchen, that could be fun to group up and prepare different parts of the meal and eat it when it's done.
3) I think the zoo has traveling exhibits (at least all of the zoos in the cities I've lived in before did). If you all are camping and doing outdoor badges, you might see if the zoo can bring some animals native to TX woods...racoons, birds, oppossums, friendly snakes, etc. and talk about their habitats and habits. You could even tie this back to environmental issues. (A local veterinarian might be able to help with this, too.)
I hope these suggestions help. And if I can help you, please let me know. I'd be happy to do so.