The final cut of the 9th episode of the Tesla Motors Club Podcast, featuring Chad Schwitters, the former president of Plug In America, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.
The fold flat seats are not 100% flat and there is some curvature to the center roof. Also the air suspension setting will affect the height from the ground. With my model X on low suspension setting, the ground to the top of the folded flat seat is about 32”. From the top of the folded seat to the roof is about 27.5” to 28.5”, with the larger distance in the back.