If you run your fingers over the the top of the roll bar/sound bar, you'll find a fairly deep indent in the plastic. You can find it in the corners also. I've used those spots to hang my dry cleaning and suit jacket. Somewhat of a tight fit but it works just fine. I wonder if that was the intention behind the design up there. Hope this helps!
I just put the rear seat (drivers side) down, and hooked the hangars to the Driver's seat headrest support. Let the clothes drape down and have the bottom of the bag lay on the folded seat. Worked out ok for my suits...don't know that I would try that with my wife's clothes though...