My 8-1/2-year-old weighs 59-60 lbs and I've forgotten his exact height but I think he's just 3 or 4 inches past 48". He sits without complaint in a Britax Frontier 85 in harness mode in my own vehicle, but when we go out of town and rent a car (which will be soon), I want to bring a backless booster with me. I'm hoping that the airline won't give me any trouble about checking the seat w/o charge even though he's past the age in most (if not all?) states to absolutely require him to be in any kind of child restraint device. Any advice on approaching the airline about this? We are flying Delta. Also, so many people I know seem to get their kids out of restraints just the second they are allowed to legally, so am I being overly cautious with this? At his height/weight, should he still be in a booster, at least? or leave it at home for the trip? I feel as though I look like a "helicopter parent." I used to be a lot more lax with my older two (now grown) kids years ago, so maybe I'm going in the opposite extreme? Advice would be appreciated. Thanks. (btw, I know that I can rent a car seat from the car rental company but would prefer not to unless really necessary)