Yeah I figured thumbin' it would be my best bet. Never been to Rainbow or hitched in Florida so its all new territory
I did this last year when me and my old road went to the Ocala Gathering. Hitching through Florida is fine, but going through GA, SC, and NC is a fucking pain in the ass. I dunno what Kentucky, Tennessee, Mississippi, or Alabama are like, but once you hit Florida it's smooth sailing. Also, since you've never been to a Rainbow Gathering, I can give ya a heads up on what it's gonna be like: 95% of the people there usually only have two things on their mind: drugs and sex. That generally creates a very superficial veil between you and the people you'll run into. Most people will be cool with you for a while, then eventually they'll inquire about doses or pot or shrooms or whatever, and if you have no ability or intention of givin' up the goods they almost immediately lose interest in you and go about their ways. If you're a girl and you're talking to a hetero dude then they'll probably stick around a while longer, but if you show no intention in givin' them some snatch then they're out. The ratio of these people to decent folks are almost entirely exclusive to the Ocala Gathering, which has a reputation for being quite the scum fuck gathering. My only other Rainbow experience was Nationals in Allegheny National Forest. That was actually okay, though one out of three or so people I met were the type I described above. There were far more people there than at the Ocala gathering though.
Not ALL people you'll meet will suck though. I have met some awesome people who are genuinely there to be social and connect with other folks, share stories, share music, and make friends. Also, on the plus side, the location is really cool. Square miles of woods with various fireplaces and camps scattered throughout the place. Trading circle is pretty fucking fun, you'll probably end up spending most of your time there. You should go packed with a shitload of cool stuff to trade. You'll be surprised with what you can score. You should also bring a lot of food you can cook for yourself. Pack sandwiches - lots of them. Food is usually served in minimal rations at the various kitchens, including the main circle feed. Plus I and many others got some wicked food poisoning last year, so if you wanna not go hungry and avoid potentially getting sick then bring your own food.
tl;dr: Most people will suck, some people won't. Bring your own food and lots of awesome stuff to trade, and take what people tell you or promise you with a grain of salt - most people are just looking for drugs and sex. Have fun!