Anyone find a HIGH BACK booster that has worked for them? I've seen a lot of old threads debating backless boosters and seat belt extenders -- please let's not rehash that. I'm just wondering with new car seats coming out every year, has anyone found a high back booster that works with the seatbelt path and NO seat belt extenders. Especially interested to hear if anyone has successfully used a Maxi Cost Rodifix or any of the Cybex seats as they all seem to have a narrow base. I have a Clek Oobr which doesn't work because of the tilted-forward headrest and the fact that it blocks the seatbelt. I've also used a backless booster for several months now (Chicco GoFit Backless) but my daughter is complaining that her back hurts and she would like a headrest, and I am thinking now I'd feel better with side impact protection. Or those with a Diono RXT: does it work for you with the seatbelt? I'm worried my daughter is too tall for the harness slots.