According to the Jeep website, the Trailer-Tow Group is available on several trims, including the Limited, High Altitude, and Latitude Lux in addition to the Trailhawk. You just have to make sure that the 4x4 option is selected, since the package doesn't come with FWD.
Interestingly, it appears that the 2.0T engine is not currently available on the Trailhawk. But don't worry -- you can still get the black-painted 17" wheels for $800 more than the gray-painted 17" wheels of the exact same design.

It costs only $700 to upgrade from 18" to 19" wheels on the Limited, and that comes with a tire size increase as well!