I gotta say, from experience growing up around Chicago, that banning a kid from ever coming back to something is not the cure to a problem; the kid becomes vindictive, and may very well end up joining a street gang (now he's become more of a problem than he was).
Just recently, I've become an Assistant Scoutmaster of a troop out here in Peoria, Il, while attending Bradley University; they are a great bunch of kids, but not without their disputes, of course. On a campout we went on last weekend, problems ranged from kicking each other while hiking in a straight line, tapping each other with sticks, purposely trying to annoy myself, and even coming close to getting physical with me. The best way I could have punished them was to simply reward them: physical workouts. I figured that since I'd be doing Personal Fitness with them in about a month, now was a good time to get them started. Everytime they did something that I clearly told them not to do (or that was against common sense, like hitting another kid in the head with a water bottle), click, click, click, they got some sort of calisthenics to do after we finished our hike. Now, some retorted that they didn't have to, so I made it simple for them; either they served their punishments, or they didn't participate in the games I would teach them. From a personal perspective, I must say that doing workouts like pushups, sit ups, jumping jacks, squats and such, it really gave them some discipline. For two of them that were having issues, I had them push a log up a hill. What was really beneficial to me was that after they had done everything that was expected of them, and before we had yet to play any games, one of them told me that this was the best campout he had been on in awhile (must've been all those endorphins, lol). Now, with the kids in your troop, spider, I'd just assign them physical workouts to do together (moving logs/ equipment/etc., doing calisthenics, and even running together). Now after they finish those things, it's important to reward their good behavior right away (kids are like puppies, in that if you don't reprimand them or reward them within 10 seconds or so of their actions, they really don't make the connections).
Hope all of this helps,
-ES316