Upgrading the transmission cooler?

I recently purchased a travel trailer with a dry weight of 3500lbs and a GVWR of 4700lbs. We plan to go on an adventure from the Canadian Prairies to Vancouver Island and back this coming summer. The Coquihalla highway along the way has a bit of a reputation for cooking transmissions.

My 2018 TRD off road is pretty much stock.

My brake controller along with my Bluetooth OBD2 reader for reading transmission temps is on order. I am trying to basically get the truck ready to take delivery of the trailer in a few weeks.

From other threads it seems the stock cooler is only good enough for daily driving, not towing anything.

Also keep in mind, in Canada, we have some pretty cold winters so is there such a thing as too low of a transmission temperature?

When it comes to the transmission cooler would you…
A) Replace the stock transmission cooler
Or
B) Add another Cooler in series with the stock cooler


After choosing either of the above, what cooler would you recommend? Do I even need to worry about this?

Pics of installs and towing more than appreciated. Thanks in advance for any help.

 

Where are people saying that the stock cooler isn't enough? Are they posting data showing this or is it "I just want to upgrade my hood bumpers" kind of stuff?

 

I forgot to mention the following 2nd gen threads seem to make this an issue.

https://www.tacomaworld.com/threads/transmission-cooler-suggestions.442540/
https://www.tacomaworld.com/threads/trans-overheated.428722/page-2

This video is also part of my rabbit hole.
https://www.youtube.com/watch?v=BMsUDmcqnl4

Will our third gens benefit from this cooler "ounce of prevention"?

 

I'm not an "expert" but I have done a lot of towing around BC and Washington State with our 19' Nash. As for trans temps, I've never had any over heating issues. The first few years of towing blind (as in no reader) and then recently with a reader, never seen it get very high. My engine and trans coolers are all stock.
Couple tips tho,
1. Make sure your equalizer bars are set up properly
2. Look into rear air bags. I put in Firestones and love them. Levels everything out, no saggy ass (head lights working as they should).
3. Carry a some fuel with ya. These truck are very thirsty when towing. You might get 350km to a tank when in the hills.
4. Carry just enough water in the trailer for pit stops. No need to tow around that much water when you can fill up at almost all camp sites / Canadian Tires.
5. Have a great trip.

Hope this help some.

 

FYI:

https://www.tacomaworld.com/threads/3rd-gen-transmission-cooler-upgrade.482280/

Some additional options/photos in this thread:

https://www.tacomaworld.com/threads/aftermarket-oem-transmission-cooler.405799/