Hi, we are flying from Boston to Miami, with 1 hour and 18 minutes layover and then on to La Paz, Bolivia. Both flights are AA flights. We really concerned about the layover time since we have to go through the US custom. And we don't need to claim any luggage. Is the layover time enough for us? Do we have to go out of the terminal, go through the US custom and then enter into the terminal? Thank you very much.