So, I think the problem is largely me. I tried a different seating arrangement, and while I had some pain associated with a new position, it was "out of shape" pain versus "bike fit" pain, I think. Mostly, I scooted my butt back further to get lower in, and while I need to get in better shape to really make it work, I think that helped. I'm going to try a different stem and bars, just to see how much difference it makes, but mostly I think this is about my lack of overall conditioning...at least based on my experiments this morning.