I've lived and worked here for almost 20 years. Not out of true desire, mind you, but out of expedience and happenstance.
You're almost right. Metro Jackson is a place where you do start to see more Cowboys paraphernalia on cars and such. But based on my experience, I'd count Mississippi as majority-Saints, with the Cowboys in second. Dak Prescott being a former MSU player has added to that in the past decade. When Eli Manning played for the Giants, there was a whole lot of love among the Ole Miss crowd for the Giants, but now that's non-existent where the Giants are concerned.