I actually have some experience here!
For reference, I'm a liberal atheist with a Philosophy degree from New York. I was a volunteer in Westchester for 3 years.
For the past 2 years I've been on the job in sub-rural South Carolina. I'm....I'm not exactly a fan. The racism in the department is actually far from the worst part; there's such pressure from HR, they're so afraid of lawsuits that you really won't hear it. My captain is black, and there's also a black lieutenant, but honestly, I think that's as high as they'll be allowed to progress. Racism is more shown more than spoken of, and really, many of the guys are well past that point
Dating black women may get you some perturbed questions, and you may have a few guys take issue with it, but that's not much different from anywhere else. If they have a brain in their skull, well, A) they wouldn't have a problem with it to begin with, and B) they'd avoid talking to HR, because that shit loses you a job.
Your civilians on the other hand? I work in a poor area, and I'll tell you outright: It's fucked. The culture, the education, all of it combines into a miserable southern flavored cesspool. Which is butter and salt flavored. Which is also universally diabetic.
Homophobia on the other hand is so deeply entrenched in the religious and hyper-conservatives aspect that NOT displaying prejudice can be alienating. In 2 years, I've heard a white co-worker use the word "nigger" all of twice, and it was not in the presence of a black man, naturally. Terms like "Fag," "faggot," and the like do tend to be prominent in some people's vernacular. I got into a long argument because I refused to eat chik-fil-a due to the company's long standing homophobic far-right stance. Most of my co-workers didn't know how to react.
Being an atheist in the bible belt makes you a pariah, being liberal makes you the enemy, and being a "Yankee" makes you uppity. The locals get very defensive very quickly, and are not very open to change.
You would be called "Yankee." They mean it as an insult, I take it as a compliment. When someone says "You don't look like you're from around here," i typically thank them. I've been called a Carpet-bagger for taking a good-old-boy's job before.
If you're content with keeping your mouth shut, head down, and agreeing with what people around you say, you'd do fine. If you're like me, you'd do it the hard way, and that took a lot of time, a shift change, and any number of arguments. It gets you labeled as a "Damn Yankee," "Trouble Maker", or, my favorite "Uppity," (an adjective which typically gets put before a racist, sexist, or homophobic slur.)
I can't stress enough that this isn't universal to the south. The fire service in general has this problem. In my experience (again, suburbs of the City versus sub-rural Myrtle Beach area) it is worse in the south, but attitudes toward social change, religion, sexuality and politics are far more problematic than the racism.
Except when it comes to anyone middle eastern. They're all terrorists as far as these guys are concerned. And Indian, for that matter. They can't always tell the difference between the two, and they're not interested in learning about any culture other than their own.
And just because I've already got southern downvotes coming my way: Lay off the sweet tea you crazy bastards, Type II is a real thing!