I am looking for a backless booster for my almost 9yr old DD. She is 57" already and all legs. I think the base of the turbo booster is too tall. I was thinking the incognito would fit but I think the threads on the side would be an issue as she has autism and will play with any straps or anything on the seat and I can see them causing problems. Any other seats I should be considering? She was in her frontier but the seatbelt kept getting stuck and not retracting. She should be able to sit good in backless. She doesn't sleep in the car so not too worried about that.