i am under 140 most of the time even if towing. I have seen it rise above this twice! And that was because i was towing a 10k excavator up a very steep hill at like 35mph!!! The other time was out of the beach doing cookies (idk why that made it heat up)
But i have a giant tranny cooler, along with a fully built to the gills tranny!! So idk how much this will help you