How about a game of Twister? Or do Pictionary, but limit it to all the things at the camp or things that have to do with what you've seen that day. Do a nature walk, taking your tree book with you and see how many trees you can identify.
Think of all the animals in the movie and ask the girls which one they'd like to be if they could be any one of them, and why.
You can make your own puzzles by having a supply of ice cream pail lids (5 quart size) and letting the girls tear out a page of an outdoor magazine, gluing it to a sheet of card stock and cutting it out in different shapes on the blank part of the card stock. You can use stencils, cookie cutters or just let them draw shapes of their own choosing. Use the ice cream lid to trace around your puzzle and cut out the circle. Now you have a puzzle tray to keep your puzzle neatly together.
Bring empty plastic salad dressing bottles, with the lids, and let them pick their favorite rock, or sand that is especially different. They'll have this to remember their trip when they're home. Put tape on the top with each girls' name displayed. Also, the three legged race is a good game to teach cooperation.
Or blindfold everyone except two people, one becomes the leader and the other becomes a helper. Everyone stands single file, with their left hand on the left shoulder of the person in front of them. Of course, before you start, without the kids knowing about it, you determine what course you'll be using. Then, the leader starts out, with everyone keeping their hand on everyone's shoulder. If one person loses contact, they and everyone behind them stops and stays quietly where they're at, allowing the rest of the group to go forward. However many make it to the end of the course all get blue ribbons. The rest get a ribbon in decending order, according to groups that got lost. The last group to fall away would be red, the next would be white, and so on. Set the course to also go under brances and around rocks, but nothing where they might fall down a hill or get hurt. The helper's job is to push on the heads of people before going under the trees, so they don't hit their head. Hopefully, the one behind will feel them go down low and will follow too. The helper will make sure they don't get hit. What this teaches is trust. No one speaks during the game. Anyone speaking gets pulled out by the helper, and the next person will step in the gap, placing her hand on their mates shoulder.
How do I know so many activities? I've been a Sunday School teacher for almost 15 years, and two of which I was a Youth Leader. I went to a youth camp for a week, with my group of kids, and the blindfold game was one we did there. I dropped out because I heard water right next to me and I lost trust in where I thought they were headed, so I stopped. Good thing I was the end of the line. The thing to remember is to think of what you've got, and with the girls' capabilities, and go with that. You can take many of today's board games and adapt them to your scout group. Of course, you can always have them sit outside and draw something that they like, to the best of their ability.
One last thing...I don't know if you know how, but when my girl was a teen, she made her own mini marshmallow shooter, out of small PVC pipe. It sorta looked like a PVC machine gun. And You could load mini marshmallows in it and shoot at targets...or each other (not in the face please!). It was quite hilarious and biodegradeable (something will eat it when you're gone). Or you can do it in a contained area and everyone has to pick them up and throw them away.
I think you'll have a great time and your girls will have many wonderful memories. Please remember to take plenty of film or your digital camera. <*)))><