old school rule of thumb:
Towing:
at the very least, have a tow vehicle that has a tow rating of 20% more than the max load you ever expect to tow. That way you should have no problem towing up/down hills, hot weather and brakes large enough to stop the load in an emergency stop situation.
in the old days to meet these numbers, if you had a trailer of any size, you would see 3/4 ton trucks, now the tow ratings of the 1/2 trucks are much higher.
I stuck a trans cooler on a 1/2 ton pickup and the next thing I had was a radiator cooling issue as the trans cooler is just another item in front of the radiator to slow the flow of air,
trans cooler, ac condenser, then radiator, with air having to travel through all of this the temp started going up
so I traded and got a 3/4 ton truck and all problems were solved, towing wise.