Thanks again Bill - goes to show how much I know about towing... I had thought that keeping RPM's down would help keep temps down, but apparently that is not the case.
Do yourself a big favor and install a cooler. Why take chances on destroying your transmission, being possibly stranded in the middle of no where. The cooler is a very inexpensive add on. But it’s your call on how you roll the dice
I must throw in here...the cooler IS a risk to the vehicle. Just make sure you get a quality cooler installed in a quality way with GOOD connections and lines. Threaded connections and braided steel lines, not rubber with compression clamps. ( been there, done that...$$$...)