You are correct Root.
From what I've seen, the ones being looked at around here are mostly juniors in their spring HS season. To my knowledge, they have all been seen during the summer on their travel teams. I would imagine it's far more difficult in your area, so playing travel is almost a must if a kid wants to play at the next level. I've never counted all the D1's within a 2 or 3 hour drive, but it's a pretty good amount.
The kids in this area, with Ivy or other high academic goals, are lucky that most of those schools are within a couple hour drive; and the coaches are willing to make the trip. At some point during the season it is not uncommon to see Princeton, Yale, Columbia and others at a game or two.
Keep plugging away. Your on the right track and your son will be fine.