So, I'm not getting a torque wrench. It was an idea that I thought of after I had snapped the first one and I was gunshy about tightening the new one too much. I installed the new one, tightened it up a bit, and then Rick Fielding was good enough to look at it and tighten it up to what he considered to be right. Rick's ear is a lot better than mine, he has done this many times on many banjos over the years, so I trust that it is correct now. However, apparently the nuts will loosen on their own over time, so maybe I'll just give them an eighth of a turn every six months or so.
Thanks for all of your input.