As for the original idea, spent a few hours measuring the CB's (at least, my CB's...) built-in EOT sensor. The devil is in the details: if the same electronics are to be applied to bikes of different manufacturers, models or even model years, there has to be a guess made on which NTC thermistor is being used. Supply voltage might be different too - just too many variables I'd be comfortable to work with. There are some 50 or so standard NTC series, not sure if I could get a reasonable readout just by guessing. Of course it could be fine-tuned to any specific bike, but that would require some way to input points of the characteristic curve - basically, taking the EOT sensor out, dipping in a cup of hot water, and measuring temperature with resistance changes as the water cools down to room temp. Not something I'd expect to be a standard installation step