Transmission cooler on top of factory tow package?

I was thinking about getting a transmission cooler, but per my vin I already have a factory installed tow package on my 2018 Ltd which, per the dealer, includes a beefier transmission cooler. What I can't figure out is what does that really mean? If it is measured in BTU, which I am guessing at based on descriptions of after market coolers, what measurable improvement does the factory package actually provide over the standard install? Is it worth getting an aftermarket cooler in addition to what I already have? There are some sales on... We are going to tow a small TT and live in a mountainous area. I am also trying to figure out what to buy if that is still advisable. The B&M models referenced in other threads are discontinued and I am trying to figure out the right physical dimensions for a stacked plate model.

 

These do not have a cooler other than the circuit in the radiator. The "tow package" is just the 7pin harness and hitch that's on all 5th gens.

Here's an option: https://www.4runners.com/threads/transmission-cooler-solution.36693/

 

I like the bracket a lot..would save my mechanic from fabricating something (which he can do but would probably appreciate not having to). However, I can't really compare the cooler options that this is designed for. I was looking at a B&M medium size super cooler that is "stacked plate." The Hayden and Derale are definitely gentler on the wallet, and for the same price I can get the brackets and a cooler. I also want to be able to use my scangauge ii to read transmission temps. Would any of these external coolers interfere with that?

 

As far as I know, no one has had issues when towing within the vehicle's limit and by not letting the tranny hunt so any extra cooling is a bonus. Maybe a larger cooler would be needed if you bypass the cooler in the rad but I wouldn't do that. Any cooler wouldn't keep the factory sensor from reading temp.