I haven't towed heavy with this Frontier yet. But I have towed heavy with the Jeep Gladiator as well as every "1/2 ton" full size on the market. 6,100 lbs. is a cake walk as long as you have trailer brakes and weight distribution to keep tongue weight in check. I pulled a 24' enclosed trailer @ 6,300 lbs. with the Gladiator regularly. It handled very good, and those trucks are known for "poor handling" if you read magazine reviews. I also noticed that if you look at the certificate of origin from the manufacturer, these midsize trucks are rated as 1/2 ton trucks. They are slightly smaller in stature obviously, but their ability to work is the same as a Ram 1500 or Chevy 1500.
I use the Curt Echo brake controller and the Husky Centerline TS hitch which has weight distribution and sway control. I can cruise at 70 with a huge trailer and it's like a Cadillac.