I'd like to suggest something that is a common cause of a lot of this behavior, that I know most people don't think about--what is he eating? When my friends have eliminated refined sugar, processed foods, and dairy from their diets and their children's diets, they have seen huge transformations in their children's behavior. Would you be willing to do that for him?
The other thing I can think of that might really help is, we totally eliminated our TV by putting it in storage, so we live in a TV-less house. What a difference in our quality of life--it is so much better. We adults watch our TV on the computer screen or iPhone after he's gone to bed...he doesn't miss it one bit. I know he'll get plenty of TV at other people's homes, so not having it in ours is a tremendous help--to us adults as well.