Well - it's finally charging anyway.
It looks like the resistor did the trick as I ran it with both voltage regulators (solid state and mechanical) and both worked. I think my initial try failed because my optimism in post 9 above was apparently misplaced and I could and did screw up installing the resistor and harness the first time - I think I managed to plug the resistor into itself. That appears to also be why I couldn't get continuity across the light leads that Bob couldn't understand. So much for cramming yourself under a dash and trying to work on little things with bi-focals.