Wheelbase of a Highlander is 109.8, I towed with a Honda Pilot (wheelbase of 109.2) you will definitely need WDH.
Horsepower on the Toyota is 270 and Torque is 248. The Honda was 255 HP and 270 ft/lb torque.
I used the Pilot for three years and I felt like I had to be "on top of the wheel" the entire time and I was towing a 2619.
It can be done but you are in the "margins." YMMV.
