I added a large piece of a Harbor Freight kneeling pad (#56572) between the seat back and the headrest to keep my kids from banging their heads' on the back of the cabin. I cut a chunk of the foam to fill the gap and then cut a couple of slots so I could weave the straps of the seatback organizers I have behind the seats. A simple strap or rope around the headrest support could also be used if someone wanted to make this themselves. I actually made the whole thing in the HF parking lot in a few minutes, after driving there with my son and having him bang his head multiple times on the drive over.
