You have no doubt figured it out by now, but the front seats must be slid somewhat forward in order to have room to flip the rear seat bottoms. For long-legged drivers, is a bit of a toss up as to whether to maximized leg room, and forsake the flat rear, or to sacrifice leg room in order to flip/flatten the rear seats. That's where the 60/40 rear really helps. The rear can be flipped on the passenger side, but not on the driver side, thus giving the tall driver the maximum leg room.
And by the way, our rear head rests have now taken up a permanent position on my garage shelf. Folding seats is easier, and rear visibility is no longer blocked. Of course, we rarely, if ever, have rear passengers, so that is not a concern.