We don't do a boot camp, but the National Guard comes twice during the summer and does a work out with the kids. It's mostly body weight type calisthenics activities like bear crawls and such.
I am not a huge fan of it because the guy that runs it yells at them and talks about winning the war and destroying the opponent and it gets a little weird. The kids seem to enjoy. It tests them and at the end they feel like they accomplished something together so it's not too bad.