My DS does not scream HG+ either to the general public. He just learns completely without effort. He loves to play with kids of most ages. He would have been right next to your DS in the snowbank whining about his wet pants.
And I don't think every HG+ kid is necessarily ready to sit in a kindergarten (especially all day) with kids more than a year older. Especially, if you're thinking of a partial (or whole) homeschool option anyway. My DS had a WONDERFUL year the year before kindergarten, and he was old for grade. He is high energy. We had so much fun that year and he learned a ton. We also started him on piano that year (which was actually the first inkling we had that something was up with him). Our kindergarten was very "first grade like" in terms of behavorial expectations IMO. Just caught your post on your DS's behavoir. Ummm yep ... sounds familiar!
And I'm right there with you on the travel! My DH might have some 1-2 year overseas work options that I'm strongly encouraging. And middle school age would be nice. We also may be able to travel 3-4 weeks at a time and he can work remotely. This is definitely part of my draw to homeschooling since we are able to swing it right now!
Anyway - vent away!