It would be a whole lot cheaper just to install a transmission cooler. They can he purchased and installed for a few hundred or less.
My Tahoe didn’t come with the factory HD towing package. I added a transmission cooler that is about 2x the size of a factory job.
Trans temps do not get over 189 and typically stay at 176° Towing a 7,000 lb loaded TT. My engine temps stay at 220° same as not towing.
The chassis are the same Despite what coolers are installed, maybe different shocks—-cheap. Maybe different cooling packages but radiators and coolers are cheap too if you need to upgrade them.
Anyway, you don’t have to spend an extra $20k just to tow a trailer. It doesn’t take that much HP to pull a TT... aerodynamics play a much bigger role IMHO...a 20 ft long full profile trailer has to punch the same hole In the air as a 30 ft full profile trailer so the aerodynamic load is the same between the two.
Setting up the WD hitch properly is important.
Thanks and JMHO
Jeremiah