What I don’t see in your calculations is the hot (operating) resistance.
That will give you an estimate of the power dissipated by the thermistor and therefore the efficiency loss.
Most modern thermistors have a very large cold vs. hot ratio, and most likely your can get away without the need to bypass it.
But you have to perform the calculations.
It’s been a while, but if I remember correctly, the thermistor vendors provide spreadsheets or other software tools which will allow you to perform the analysis quickly.