I think this is right:

If Chapin wins, they win the region outright. If B-C wins 1-0, it goes to a tie-breaker which I believe may be records against 4A & 3A competition, or records against common opponents outside Region IV-3A. If B-C wins 2-1, 3-2 etc., Chapin earns the #1 seed due to away goals. If B-C wins by 2 or more, they earn the #1 seed.