What do you mean "book through"? If separate record locators, your bags would only be tagged to MIA and you would need to get them re-tagged. However, as ajleonard points out, you'll need to collect them in MIA anyway for customs, so the step of putting new tags on them won't add much if the inbound flight is on time. Your biggest issue is that you've given yourself little margin for error if the flight is late.