Cooling is cooling, oil, trans and coolant. cooler fluids will help boost performance (to a point).
I tow my 7000lb boat, and for awhile my truck was stock. It didnt have a problem with it, but like most here have said, I opted to cool my truck down.
I have an additional oil cooler, power steering cooler, transmission cooler, a 180* thermostat, and I plan on doing the heat-sinked oil pan and an E-fan in the very near future.
With a gas engine, you dont have to worry about it being too cold as long as you dont live in canadia or alaska
. Seriously, as long as your op temp is above 120 and never goes above 200 or so, you should be good. I will check again on my trip today (unloaded), but I am pretty sure my truck never goes above 150.