My daughter is 6 1/2 years old. She has been harnessed in the middle of the 3rd row of our 2015 Suburban but has outgrown that car seat. She rides nicely in a high back booster in my sedan. She wants to stay in the middle 3rd row but the issue is there is no latch system or head rest in the middle of the 3rd row. I really want a latched high back booster but it would do me no good in the 3rd row. I don't like the idea of the booster not being secured when no one is in the seat. She doesn't want to move to the bucket seats. What are my alternatives? Am I being too restrictive about this?