I think your list is pretty balanced. A few others you might consider that are similar to Hobart are St. Lawrence and UVM. Your reaches may be really tough, especially TO, but his story is a bit unusual (homeschooling, BMX, Hispanic) that it could make him stand out.
Eckerd in FL might be one to look at just to see what Marine Science programs look like. Not sure if the Pacific Northwest would be an option, but there are a number of schools with outdoorsy, down to earth vibes that have programs that might interest him. Would you throw those in the mix or does that just complicate things?
Confirm that Colby Sawyer is committed to his interests - I think they were realigning their programs. Pretty sure Environmental Studies is “safe”. Also make sure you have financial safeties in the mix. Some of the ones that are the most generous with FA have single digit acceptance rates.