To the OP, my bet is your Frontier would pull that KZ Sportsman just fine. A little slow on the hills, but it will get the job done.
The "factory" receiver hitch is a Curt hitch that is actually rated for 800 pounds tongue weight.
I'd use a basic weight distribution hitch with an anti-sway add on attachment and I would tow it anywhere with confidence. Take it easy on the clutch, which is always good advice.
The Frontier is a sturdy truck.
You can verify the part number, but I'm pretty sure this is the correct part number:
https://www.curtmfg.com/part/13241EDIT: Do some research on the "frontal sq ft limit". Nissan lowered that from 60 to 30 some years ago without making any changes to the truck. A guess would be it was part of being able to market the truck as J2807 compliant.