I am looking for recommendations for a FFing car seat (harness to booster?) for airplane travel. I'm looking to use the seat for my 4.5 year old who is 41-42" tall and wears size 5 t-shirts. We will use the car seat to get to/from the airport, on the airplane and as a second car seat to use occasionally in our second vehicle. I'm not looking to spend much. I already ordered a Radian but it was shipped by boat (I currently live overseas) and it probably won't get her in time for our trip back to the USA. Thanks for any advice!