We have more than our share of Yanks here but Florida is Southern once you leave the tourist areas. Considering that I came from what's known as the Redneck Riveria or Lower Alabama, and I'm 100% Cajun, I'm pretty sure I qualify as Southern.
That's not all that dissimilar from Texas. Dallas, Fort Worth, Houston and Austin are full of people that are from somewhere else. Once you get outside of the big cities, the people are pretty different.