Some general comments on the topic...
As for film references, an interesting model is Oliver Hardy... ( as in Laurel & ).
Oliver was from Georgia, and while his speech in the talkies does not sound like "deep Southern-fried cracker", certain words do have a characteristic twang to them, for example: "word", or "heard", which Hardy delivers something like "hoid", or "woid"... not quite so much as Archie Bunker ( Carroll O'Connor was an unapologetic Brooklyn-ite ), but in that direction.
I have heard other speakers from Hardy's generation speaking the same way.
As for the disappearance of regional dialects, sadly mass media and the internet has done a lot to "homogenize" the way we speak.
And as for "not being able to speak like where you're from", I grew-up near Baltimore, MD, which had a pronounced accent / dialect. My mother and father, who were both born & bred within 15 miles of Baltimore did not have the accent, nor did I... and, sometimes to my frustration, I cannot speak "Bawlmore-ese" for the benefit of my friends, try as I might... I think in another generation, it will be gone.
Here's a slightly embellished, but pretty darned accurate guide to Balwmer-ese... working-class, perhaps, but this guy's schtick is well-grounded in truth... I've heard it for myself many times.
https://www.youtube.com/watch?v=KylF4mZXf1Q