I have a 3yo son, and 20mo daughter. We are planning to have a third within the next year or so. 3yo is currently rear facing in a Radian and 1 yo is RF in a Nextfit. The 3yo is at the RF height limit in the Radian. Radian was in a minor accident today and is being replaced. We need a new car seat. Should I buy a Clek Foonf to extend the RF as long as possible or just flip him FF and buy a booster? If so, which booster? He is 41in and 39.5lbs. Thanks!