Trailblazer and 2720SL

So far towing with the Trailblazer has been really good. It has a I-6(275hp/275 lb.-ft. of torque). Easily maintains 70mph. While most of our camping excursions have been in Nebraska and eastern Colorado, we have not attempted to pass over the mountains.

I am curious on how many trailmanor owners have a transmission cooler?
Is it recommended, for all towing? or only strenuous mountain towing?

We do not plan on trailing over the Divide but maybe once a year(if we get the chance).