I'm not sure how many people here have automatic transmissions in Hilux, Tritons, DMax's etc etc.
I have the auto in my Hilux and although I have had no major issues with it when towing I have read about others that have. I have had the trans light come on a couple of times and have just backed off and slowed down a bit and the light goes out.
It has been pi$$ing me off that one day the trans may let me down if pushing into a head wind or on a hot day.
I have just had a transmission oil cooler fitted and I am extremely happy with it.
We went to Mildura on the weekend towing the Jayco Hawk, and gave the trans a good workout to see if the cooler did it's job.
No worries... I punted it real hard up some hills and overtaking a few times. The light never even looked like coming on.
The cooler was not cheap, $450 fitted, but it gives piece of mind that my trans is not going to overheat.