Make some phone calls. You may find gas more easily going across on Interstate 75 and up the West Coast.
Ted
Here's a resource to use as well.
GasBuddy Gasoline Availability Tracker
Now, availability is only as reported to them so normally their tracker has very little information. Type Dallas, TX or even Houston, TX and you'll see what it can look like.
Type Fort Lauderdale and you'll get a lot of information. It looks like about half the stations have gas here so you can imagine the lines.