Thanks! I was worried about someone coming up to my car, but I had my pepper spray in the middle console next to me and luckily it seemed like the parking lot was used by other campers.
I'd get my bedding ready at the gym before I drove to Walmart so when I arrived I wouldn't be putting on a show to other people to see I was preparing to sleep in my car. I'd try to be as discreet about it as possible!