This thread was difficult for me as nobody wants to be put into a position to say ..."WELL if you ony did that and this and dat...."
Not the answer, as I think we all here may have made huge mistakes that almost cost us our lives (in retrospect)
However, it is human to explore and learn as we struggle through our adventures.
North of where I live, at full flood, the current can get to be 12 knots as the entire Gulf of Georgia tries to squeeze through tiny flow points between the mainland, numerous Islands and a landmass as large as England, Scotland, and Ireland (Vancouver Island).
I regard the stretch between the keys and Cuba as having the same type of properties. As the Gulf flow goes North up the peninsula of Florida the ocean flow flow just seems to just get faster (The Bahamas). (a double venturi effect also enhanced by semi tropical water currents hitting cold Atlantic layers that thermocline under the Gulf Stream)
The standard 3 lb. 'claw' anchor seems to be the norm. Your addition of a 2 foot chain is smart as it helps to keep the flukes at the ready to grab sand, and keep them there. (However other anchors' claim to fame is at your discretion as there are better systems out there than a foldable claw in sandy bottoms)
(May I ask that you consider attaching the chain to the 'bottom' of the anchor and use a light wire zip tie to attach the opposite end of the anchor to the chain or anchor rode. That way if you snag a reef or fixed rock, a sharp jerk will break the zip tie and free your anchor. Also a free running float is very helpful if you have to pay out anchor rode to bring yourself in backwards) for retrieval.
I wish you my best SNJ