Out of a dozen or so, only one used their belt to lash things together (of course, for most teenagers, they don't know how to use a belt the way it was intended!)
Another 2 figured out that they had laces on their shoes. One of them was so frayed that they used it for dry tinder!

I don't know if Deet is flamable, but, the combination with spray propellant seems to make a nice torch of sorts. (At least until the flame gets back to the finger on the plastic tip of the spray can )

You're right though, the idea of only letting them take the bare minimum, is so they try to improvise. To a certain extent, it works. The next day, we do a "post-mortem" examination of what happened the night before, it's always interesting to see what they perceived, and learned, compared to what we saw.