Thank you all so much for your help! We are going to pack any alcohol we bring home in our checked luggage so that it is not confiscated coming back into the US. We live in Atlanta, so we'll have a connection from Miami to home, and I'm not going to take my chances.
You won't be able to pack duty free in your checked luggage. You have to check your bags when you check in for your return flight and you have to show your return ticket to purchase duty free.
You will have to put the duty free booze in your bag after you pick it up in Miami before you go through customs for your onward flight.
Of course, you won't have this problem if you buy regular priced stuff in San Pedro.