I like that you said "no-no". Chances are any adult at his school would probably be worse off than a student w/ the camera. I still think he could pull it off with how he wants to approach it. If you could put your camera up on a trip pod, or super clamp it to something like a pole w/ a wider angle lens. What you're trying to do isn't very conservative... which most school events would be. If you put it up on a tripod you run the risk of some pre-teen that hasn't learned to walk properly knocking it over.
If you do it right and maybe toss a Hannah Montana track on there this might be the best recorded spelling bee ever.