If your shooting with the 1DX then you need the 600 I often need more reach with my 500 and 1.3 cropped 1DIII I would also find a way to bring the 7D II if your allowed two carry ons this should not be a problem if not just wear it around your neck. I know everyone who comes to Florida has Circle B on their list but I have never found it to be reliable the same for Sanibel and Ding Darling I would spend those days in Ft Desoto or Estero.