To be fair: I haven't towed for such extended times in these environments. But how does this compare to the TFL towing tests with the 7.3L at the Ike Gauntlet? Seems it's doing a marvelous job there too.
I take things like TFL with a grain of salt.
How does me towing a heavy, wide, modified raptor on a heavy trailer compare? Not sure. I'm speaking from my experience.
When I tow, it is never for under 500 miles. Usually, a one-way trip is 1900-2000 miles.
I've towed in various areas of the country with the combo of steep grade, lots of turns, and anywhere from 30-50 miles of them.
towing through the vail pass in the snow? I wouldn't have done it in a gasser. the weight, torque, and exhaust brake make a HUGE difference.
Towing the 8 to SD in the middle of summer? Even with all of the upgrades, My trans still got pretty hot, as did my coolant temps.
Towing in Baja? I'll take the diesel too. The control that comes with being able to slow down, but still have more than enough torque makes me more comfortable.
So while I don't know what the "ike gauntlet" is, I do know how my truck performs in the areas of the country that make me most nervous. (and makes me confident in my equipment).
I'll also say that having 120 gallons of fuel onboard and being able to get 1100 miles before having to look for fuel while towing 12K lbs is REALLY nice. ( even though I obviously need to stop for bio breaks between fillups).
YMMV