Here is an interesting observation I have noticed here on the forum. Folks often say "I had to have that engine wound out on hills".
Here's a comparison between two of the vehicles in my stable used for towing. My Frontier sometimes needs to be "wound out" to 4000 rpm to climb steep hills, 4000 rpm is 64% of the 6250 rpm redline.
Another tow vehicle at home is a powerstroke Ford diesel. It often has to spin 3500 rpm ( and be blowing 28 pounds of boost ) of it's 4000 rpm redline when towing my 14K pound horse trailer.. 3500 is 87% of 4000.
Which one is more "wound out" ? Which one is experiencing more stress (28 pounds of boost is quite a bit ) ?
Which one is being subject to greater stresses as related to piston speed ( normally quoted in FPM ).
By the way, both these engines have a lot of miles, both with a lot of "towing miles", and both are still running well, get the same fuel mileage as when new ( both trucks bought new by me ), and neither use any oil. So at least in my tiny sampling of two vehicles here, "winding them out on hills" has apparently not harmed them.
Just some things to chew on.
EDIT: looking at the manufacturer website for the trailer in the OP's post, I agree it's too much for a Frontier.