You most definitely need the crew cab. Child seats, particularly the convertible type you have to use rear facing until the child is at least two (it's safer to go a lot longer) take up a LOT of fore-aft room. Even in a crew cab some of the child seats will hit the back of the front seats. Plus, you have way more room to load the kid. I live in Texas, which has a climate much like Florida, and I don't think you'll use the 4wd much. On the other hand, you'll use the extra room in the crew cab every day and be glad you have it.