Does anyone have any experience with these? I need to get one for my son. He is 8 years old. 54" tall. 60 lbs and has roughly a 20" torso. He typically rides in his frontier 85 in booster mode. The reason I want to get this for him is because he slumps over terribly when he falls asleep. To the point where he his head is almost touching the seat in front of him. I have to wake him up repeatedly to try and get him to sit up. He has cmt 1a and is low muscle tone as well as a bunch of other things. I plan on ordering it next week. Any experience would be greatly appreciated. Thank you in advance.