Paulx,
There is something not right in the setup. That truck should easily be able to pull that trailer in a very comfortable manner.
I would start with all the basics, and build from there.
Fresh suspension on the truck ?
Ball joints, tierod ends, etc, as new ?
Tire choice and inflation.
Trailer tire choice and inflation.
Trailer chassis all correct.
Experiment with different WD settings.
EDIT: you said the truck is a '14, so I am assuming it's very low miles, so we can assume the front end components are still as new.