I probably didn't explain myself very well (...because I was in a hurry that day...) but I was a GM company vehicle driver for nearly 20 years. That allowed me to pick any vehicle in the fleet to tow my trailer on race weekends.
Trailer is approx. 7500 lbs fully loaded.
You noticed the same thing I did as we (as a company) moved away from diesels/big blocks and into the small block variants*. You really have to spin them, which results in going down in gears, to maintain your ground speed. I suggest that is what you are perceiving as "struggling".
Even if it is not bad for the engine it is more annoying than simply torqueing your way through.
K
*I worked on six generations of GM full size trucks:
Old C/K/R/V
GMT400
GMT800
GMT900
K2
T1
That puts me in the somewhat unique position of being able to see for myself this transition across the years.
