Much of the drivetrain of the vehicle is identical to the 1.4 TFSI S-tronic, which is rated at 1500kg towing capability.
The main difference is the addition of the electric motor, which shouldn't be impacted by the additional load - it's limited by current through the controller, not by anything that would wear faster with additional load. I imagine it may be possible that the engaging and disengaging of the gas engine could be impacted by the additional load, both in the control programming as well as the mechanical actuation. If you were to try towing, it might make sense to run in sport mode so that the gasoline engine always runs.
Just my 2 cents; I'm considering trying it this weekend with a load approx 1/2 the rated load.