As much driving as they did that night, I'd guess there was a gas fill up. Possibly a meal, though DE likely had blood on him unless he changed clothes. Perhaps a restroom stop. There's a big rest area on I77 right over the NC border. I'd expect security cameras there since it's a big visitor center.
Yes, all those security cameras.
The ones at the Walmart they went to with the body in the trunk to buy cleaning supplies should be an interesting one. Where/how did they clean up before they went in there? If they had a change of clothes, maybe they dumped the bloody ones at Walmart.