Good points, mainly on the ugly.

All my fittings came from summit in one form or another. I used two, and the first has the proper taper for the sending unit seal ring, accuracy and sealing was/has never been a problem. The strictest tech tracks never said fix it.

Im sure he can do it with one.

How do I know how accurate the manual unit is installed this way?

Look at this pick, thats the t stat for my 2nd (backup) ele. fan and is said to be a 180 degree unit, the few times ive got that warm, manual unit said right at 178/180. Real world testing, not "I think" or "It might".