JonA -
Welcome, glad that you asked. My son is 2E so we haven't had to face this in our family, but we know many people who have -
1) If you want to keep the door open to being a Freshman at a super-selective school at 16, the key is to 'homeschool' that last little bit of Highschool, so that he doesn't officially graduate at 14, but can be a 'dual enrolled' high school student. That way he can take local day classes to his heart's content without having to try and enter a super-select school as a transfer student, which is much harder and less financial aid.
2) There are amazing schools that he could attend and live on campus at a very young age and get a lot out of because they are so structured
http://en.wikipedia.org/wiki/St._John's_College_(United_States)
comes to mind. Particularly if he is more interested in the Humanities Path.
3) If he is more interested in STEM, then getting involved with local research is a way to go.
4) Log on to College Confidential and take a look at the schools that you think might be a good social-emotional match and see what good candidates are looking like. That might give you an idea of some activities you child would find rewarding. I'm NOT saying you should try and shape him into what you think the college might like, more that, since it is a good social/emotional fit, you may find great ideas to pick from.
5) Summer programs are a great way to get with real peers. Advertised age isn't always the same a real age. I was just reading see question #13
http://www.hcssim.org/faq.htmlIf you child hasn't done THINK summer program, a wonderful one.
6) It's still so early. You child will probably develop at least one major new interest in the next 2 years. Perhaps it will be in an extracurricular area. You will get to see if his 'organizational skills' and 'physical stamina' are up to doing work with kids at plus 4 chronological age. Or maybe he'll still be so underplaced that you won't really get a chance to know, but it's a start.
7) Look for a mentor at one of the commuting distance schools so he'll have some intellectual companionship along the way.
8) Join DYS and get on their listserve for early college - there are very kind parents there who can answer specific programs about specific places.
Hope that helps,
Keep us posted
Grinity