You might consider visiting the school specific threads for more information on the Puerto Rican schools (and you might calculate what your new BCPM GPA could be after a one-year or two-year postbac).
As an alternative, if a second year of straight-A postbac work would get your cGPA above a 3.0 and you got a better MCAT score, you could qualify to enter a Special Masters Program that could redeem the undergrad GPA enough to get you considered by a mainland-US MD school. See SDNs Postbaccalaureate Forum for more details.
I suspect that the Caribbean schools will be your best bet though if you're in a hurry.