We will be renting a minivan for our November trip. We are bringing the carseat for our 2 year old, but I don't know what to do about our 4 year old. Right now, he is in a booster seat, but since he won't need it for the plane ride, I'm not bringing it with us. Do I need to rent a booster seat from the rental company or can he sit without it? He is 41" and 50lbs. Does anybody know what the law is in Florida regarding carseats? Thanks.