I would second the Kalamazoo recommendation. K would offer the attention and support your son needs, while also giving opportunity for independent, hands-on experience. Lots of businesses in the area, too! I believe K works on terms, which means only three classes at a time- that might really be of benefit to kid who gets overwhelmed. Their graduation rate relative to their selectivity is impressive, which also suggests students are getting great support.
I might also suggest Beloit. We toured recently, and our guide was a lovely, very bright kid studying quantitative economics (? something like that) with the goal of working in finance/business. He was thrilled with the education and support he was getting, as well as the connections he was making. The admission office is personal, so if you tour, you could probably even request him as a guide. Beloit’s sweet spot seems to be working with bright, curious kids who aren’t necessarily type-A performers.
Doesn’t sound like you need merit aid, but for anyone else reading, both schools are generous with merit.