Oh and one of the guests is a Jewish cardiologist so I can't rely on a wholly pork based menu!
Well it depends on the sort of dinner party you are having. I have some ideas for a less formal dinner party: cornbread, pulled pork or beef, pies of all sorts can be made ahead, sides like butter beans are easy to throw together early, you could probably make grits ahead and just add more liquid when it comes time to reheat and if you'd like to do shrimp and grits the shrimp can be done ahead as well. Maybe if you give us more of an idea of how formal the affair will be, it will be easier to suggest items to make! Good luck :D
Another suggestion for an informal party: Texas chili! You can make it in advance and just reheat it whenever you want. It's all beef (so it won't be any problem for guests who don't eat pork) and it's so much fun to make if you have the time.
I'm all in for Southern fried chicken, mixed greens, corn pudding, corn bread & iced tea. Perhaps a hummingbird cake or ambrosia for a sweet ending. A few do aheads in there. Homesick & hungry!
There are a lot of great entertaining ideas in the Lee Brothers cookbook. Hugh Acheson does this great appetizer called things in jars - it is pimento cheese with bacon jam, deviled ham, smoked trout dip and boiled peanut hummus in jars with crudite. I agree with the shrimp and grits, that's my go to. You could put the grits in a crockpot to cook. Pan fried trout, lightly sauteed collard greens, beef short ribs and grits, brussels sprouts, pink eyed peas, corn bread casserole
Black eyed peas (with a pork free smoked turkey leg).
Both can be made the night before.
Peach or Apple Cobbler; or a pecan pie or sweat potato pie.
For Twenty people? Will this be buffet type service? Add a shrimp dish (Maybe an etouffee), meatloaf, creamed corn, and potato salad. All of those can be made ahead an reheated. With MAYBE, MAYBE the exception of the etoufee--I've had it the next day and it's just fine.