Wirelessly posted (BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
I do not know if it is still the case, but there was a period of time when passengers transiting MIA from an international arrival to an international departure did not have to claim and re-check their baggage at MIA. Although the passengers still had to go through all formalities, their checked bags were not seen until arrival at their final destination.
Perhaps someone with more recent experience transiting MIA can clarify whether the same process is still followed today. Or the OP might try contacting U.S. Customs at MIA.