You have a few choices depending on what you would like to do.
Carowinds: www.carowinds.com Large pull throughs with 50amp. Attached to the amusement park. Right off of I-77
Fleetwood RV park. Next to Lowes Motor Speedway. www.lowesmotorspeedway.com go to the camping section. Large sites. More of a race event cg but does have pull through sites but those do not have cable tv. Right off of I-85. Large outlet mall, many places to eat.
McDowell Nature Preserve. Near Carowinds. Has a couple of pull throughs that can accommodate your rig. However, no sewer but does have 50 amp. Inexpensive at under $20 per night. It is a county park.
Charlotte / Fort Mill KOA. Off of I-77. Mixed reviews. Not bad for a stop over or "home base" type of visit.
High Rock Lake CG in Lexington. About 80 miles N of Charlotte but nice facilities on lake with fishing pier and boat rental.
Hope that this helps. Visit www.rvparkreviews.com and look at Charlotte, Fort Mill (South Carolina), Concord NC, Lexington, NC
Fleetwood RV Park next to the Lowes Motor Speedway in Concord. McDowell Nature Preserve... but, your size might be an issue. Paramount's Carowinds Campground... touristy and reflected in the price. Fort Mill KOA... very easy access from I-77, but not my cup of tea. And MY favorite... Ebenezer Park in Rock Hill... lake setting with a low, low price. A gem. Best value. Problem is... first come basis, very popular with locals who place tents on the sites to save for neighbors. During camping season, best chance to get a site necessitates arriving on Sun-Wed afternoons.