the thermistor technique requires that the fuel tank be stirred so that any variation in mass may be accounted for.
WHy not meter in known volumes of gas, say a gallon at a time and then record the actual reading on the fuel gage(Or install an after market fuel gage that they use on ralley cars). You will(if you are totally anal about this, need to measure the fuels temperature to account for any degree of expansion.
Ill bet that, even with all this "improved accuracy", you wont record any big differences in fuel readings. The difference between 1/10 a gallon and 1/100 gallon wont have a big effect on your mileage or economy unless you go all the way and install a really accurate GPS based odometer and a more accurate speedo and tach.