Thank you for your service to our country from a former jarhead! Freedom isn't free. How long until you have to be in Alabama?
Have you camped in military famcamps? There are lots of those in the Florida Panhandle. check them out on www.militarycampgrounds.us
About 3 hours south of Enterprise AL is St Joseph Peninsula State Park. http://www.floridastateparks.org/stjoseph/
Another FL state park is Grayson in Santa Rosa Beach.
Not many places you can camp right on the beach, but Camp Gulf in Destin is one of them. Very expensive but right on the beach. There is also a military campground in Destin. Destin Army Infantry Recreation Center. Not on the beach, but near. Florida Caverns State Park in Marianna is a small cavern but neat to see. In Gulf Shores Alabama National Seashore, there is a ferry you can take to West Ship Island. Camping at Fort Pickens and Gulf Shores. Bring bug spray!