Reason I ask is last week I was in upstate NY, got caught off guard by the terrain and had to climb a freakin mountain with my race trailer (4-5k lbs?). I was in 1st gear the way up and 1st gear all the way down... transmission temp, according to my Bully Dog GT reached 248*F and I was crapping myself.

I performed the bypass when I purchased the truck at 84k miles and I RARELY ever see trans temps above 220*F when towing but this last trip has me wondering if I should install an additional trans cooler or electric fan or both.
Last trans flulid change was about 40k miles ago.... bout to change it out again now that I'm towing heavy.