Hi george, I do not know about commercial tandoors but I tried a temperature probe in my nipoori years ago when I first brought it as I could not believe it could produce temps of 400C.
It did and actually went above up to 430C with the hottest area actually being right beneath the top opening not immediately above the coals as you would have expected - it still amazes me today and I was the biggest skeptic in the world. I will see if I can get my hands on another probe and the next time I fire it up I will take some recordings with photos hopefully.
bon regards