LOL! Very ingenious Tim!
A fish scale can be had at most hardware stores or anywhere they sell fishing supplies. Couple of bucks. Doesn't have to be that accurate, just within a range of turning resistance. The reason is that the rotational resistance is a more accurate gauge of proper bearing preload than the adjusting nut torque. The torque is just a rough guideline. If the torque (of course you must always back it off 1/8-1/4 turn after the torque is achived) gets you to the proper range of preload, you're fine. I was also taught that while you're checking preload, you should rotate the wheel a number of times to make sure you drive the grease from the roller-race surfaces to get a proper reading.
Below is a photo of using my fish scale to adjust the preload on my 76: