If you don't have anything against KOAs, most of the KOAs in North Carolina are nice. It's been a few years since we stayed there, but we really liked the Smithfield KOA in Four Oaks, NC (exit 90 of I-95). That's about a 300 mile trip, so fits into the 5 hour drive with ease. Four Oaks to Annapolis is just over 300 miles, so without traffic, 5 hours will do it.
If you want to stretch it out across three days, I would recommend the Fredricksburg, VA KOA. It's a few miles off I-95 (heading North, I believe it is exit 118). We stopped there when our tow vehicle broke down and really liked it, even though we were stranded there.
Or you could drive up to Williamsburg, VA after leaving Smithfield and spend a day or two there. There is enough to do in Williamsburg to warrant spending two nights there. I've never camped in Williamsburg, so I can't recommend any campgrounds. Then drive to Annapolis from Williamsburg.
-Michael
Michael Girardo
2017 Jayco Jayflight Bungalow 40BHQS Destination Trailer
2009 Jayco Greyhawk 31FS Class C Motorhome (previously owned)
2006 Rockwood Roo 233 Hybrid Travel Trailer (previously owned)
1995 Jayco Eagle 12KB pop-up (previously owned)