LOL! How do you know they are "doubtful"? Are you a prophet? International trade and law enforcement involving international, national, and state authorities and their citizens are highly complex matters. The drug trade is enormously lucrative--legal or not. Vast amounts of money warp any and all accomodations and arrangements.
Common sense tells you that if things can go wrong, they will go wrong. I don't need to be a prophet to assure you that no only would these kinds of untoward events occur, they occur in greater numbers and have worse effects than I've listed so far. What you are proposing is to fracture the United States into a confederation of fiefdoms that would be allowed to be at complete cross-purposes with one another on matters of border control and trade.
The founders tried that route once, rejected it as wholly unworkable, and adopted the present Constitution in its stead. Let's not return to failure.