Thanks again for the brain waves, gang.
MD, I'm not sure if I really will need SD calculations for my needs, especially now as the shakes are a factor, but it seems like a hun or two to keep me safely away from the Stupid Zone isn't a bad investment. It will be kind of like how I used to use mileposts, second hand, and the tachometer to tell my speed when I was too poor to buy a speedo cable. Or, if both were broken -- I still knew how fast I was going in each gear.

Up hills slow,
Down hills fast
Tonnage first and
Safety last.