@ChanW, I guess the issue of extending the temp sensor cable is now moot. For what it's worth, there was another opinion on that which said: "These temperature sensors are simple resistance units, so extending the cable any reasonable amount is perfectly fine. Use minimum 18 AWG cable to ensure no extra resistance in the cable could affect the measurement."
I had been wondering how you could only have the temp sensor cable to route from inside to outside, but thought maybe you were moving batteries inside. Anyway, good luck - I'm sure you'll get it all sorted out. Take your time.