If you look at this chart - you will see you were in Warning Areas much of the time. You also have to ask for permission to enter the US ADIZ. The MSA for much of the journey is 400 or 700 feet.
I could almost guarantee that flying at 300 KTS at 100 ft AGL would get you visited by some fighters out of JRB Homestead or NAS Key West. I drove to/ from Key West from Fort Lauderdale a month ago and the blimp was flying both days. There were also P-3 Awacs aircraft flying out of NAS Key West.
Also, at 100 ft AGL - you have to be really careful of ships coming in or out of the Gulf of Mexico. Some of the cruise ships going into Key West and through the Florida Straits have passenger desks 100 ft above the water. The Oasis of the Seas is 236 ft / 72M above the water.
Many cargo ships have super structures near 100 feet above the water, especially the big container ships.
@ PawPaw's house - near KADS, Addison, Texas, USA