I agree with Rock Hill, which is 30 miles south of Charlotte that will have you out of the AM Charlotte traffic. If you choose Rock Hill, stay at one off of Dave Lyle Blvd and avoid those off of Cherry Road.
Since you have a fifth wheel, look at Ebeneezer Park. It is a nice quiet county owner park on Lake Wylie in Rock Hill. It is about 7 miles from I-77 and runs $29 per night for out of county rate. Seniors get a $4 discount per night. I see that you don't want to dewinterize, but they have nice clean bath houses.