we have a similar situation, very capable truck but with a small engine. in our case its a dodge Dakota but with a v6. we tow around 4000 lb.
long hills are a challenge, days with a strong headwind are painful
we just drop down one gear and let it rev away!! long upgrades will push the revs upto 4000 rpm but we slow down so that the noise is less and we watch the temperature guage, never had an issue with overheating though
regular flat towing with no head wind is easy, we can easily maintain 110 kph, engine revs are around 2700 rpm, quiet and comfortable,
I just wish for a small diesel!!