First the ones that I have direct knowledge of:
The Impact Summer Showcase is usually very well attended by various sizes of NC and some SC colleges. It is July 1&2 at Wake Forest University this year.
Perfect Games Atlantic Coast Top Prospect Showcase has also been well attended by Carolina schools in the past. It is scheduled for August 11&12 at Coastal Carolina this year.
Elon University has an all skills camp that is usually scheduled for November that is pretty well attended by coaches from NC a few SC coaches work as well.
Now for others:
I have heard that the Blue/Gray at Wake Forest University, scheduled for sometime in August, is pretty well attended.
Those are the best that I am aware of. Hope this helps.