Thanks, Brian. Not sure I'm sold on the idea of vapor barrier yet, but I will make a more serious effort at "tapering" down my exertions so that I can balance this out a bit more.

My wife, of course, is just the opposite. She can hike in full cold weather gear for hours without warming up, but when she stops, she stays the same temperature. So I am shedding clothes right and left as we hike, and the shivering when we stop. She starts out by laying up...and then stays warm even if we stop for half an hour!