It was idling in the images with the DC voltmeter. I can try it at 2,500 rpm with and without headlight.
I didn't look close enough and I guess I somehow understood this voltmeter to be inline measuring the voltage flowing through it, not just reading voltage like a tester. Like I said, I'm not a EE

Anyway, in the end I think the regulator has at least one fault for me to correct before any more testing.
Please let me know if anyone has thoughts on the specific fault in my regulator that could be repaired, or a way to integrate an off-the-shelf regulator into the system to bypass the problem.
Thanks!
Jim