It's probably more of like a crumpling creaking sound. I'll re adjust the back seats and see how I go. In the mean time I'll take out the rear cargo shade as I never use it. I'm also thinking it could be the sunroof fabric when closed rattling.
Shot in the dark, but does the creak go away when you open or vent your sunroof? Mine creaked when I closed the sunroof and then with the sunroof closed would creak intermittently when going over bumps, etc. Finally got around a few days ago to putting silicone grease on all rubber and plastic contact points where the sunroof closes and that immediately got rid of my sunroof creak.
2014 Limited, 4x4, 3.2, 8.4 NAV, Luxury, Panoramic, Deep Cherry Red Chrystal Pearl