“North” vs “south” would depend on which direction you are going.
I think it depends on where the river is going.
I’ve lived in central FL since 1996 and I travel all over the state for work. I don’t recall hearing the term before Idalia, but there just isn’t very much there. Due to the nature of my work, I’m familiar with thousands of orthopedic practices but I don’t know a single one between Hudson (just north of Tampa) and southern Tallahassee.
Looking at my copy of Tim Hollis’ 2008 book Selling The Sunshine, the jacket cover blurb says “…the book is arranged according to the state’s traditional tourism department regions, including the Miracle Strip, the Big Bend, and the Gold Coast…” So at least some folks have been using the term for awhile.
One of my absolute favorite spots in Florida happens to be in the Big Bend: Edward Ball Wakulla Springs State Park. As the State Park motto says, to me it’s “the Real Florida”. Jumping off the diving tower into that crystal clear spring water has been a highlight of all of my visits to the state.
My gender-neutral sibling! I have no way to count how many times I’ve gone off that tower or done the glass-bottom boat tour. Wakulla Springs is a gem. The restaurant is pretty damn good too!