We have a 2015 Highlander that DID NOT come with the factory towing package. We added the hitch and wiring harness ourself. Our primary purpose for this was to be able to haul or golf cart with this car while the TV hauls the 5er. The golf cart weighs roughly 1200 pounds and the trailer weighs roughly 750 pounds...so very roughly the combo weighs around 2000 pounds. Its a small footprint and represents little to no aerodynamic drag issues, such as what you might experience with a travel trailer.
Based on my experience, I would prefer to not tow much more than what we're towing right now with our highlander. Short trips on flat ground would be OK I'm sure, but the Highlander is far from a suitable TV...IMO. Otherwise, we love it as a general purpose vehicle.