Get him in with the boarding school counselor when they go back. All boarding schools have them on staff, many have 2-3. Leaving on the weekends will end up hurting his social life. The kids who leave, just don't fit in as well as the kids who stay and are forced to participate in the social stuff and make friends that way. Call the school right now and tell them he needs a roommate that is going to be around and also on a team, and will be there the first day.
My DH works at a NE boarding school that is sports heavy and we are deeply engaged in the culture. It's like college, you need to be all in or not in.
Do you know who his advisor is? Have you talked to them? What about student life and the health center there? Feel free to PM me, I have a good sense of most northern NE boarding school culture and might have some info. We have been in the world a long time.
Tracey
DD1 3/07 Itching to take over the universe.
DD2 1/14 My mellow little snuggler.