I must disagree with the majority of posters to this topic.
Wal-Mart has made it known that they welcome RV'rs to park overnight. (park, not camp) Those locations that do not always have signage posted in the parking lot saying otherwise. Parking at Wal-Mart overnight means park in the outer areass, arrive later, leave early. Slides out is always and option as many MH's are not accesable without the slides out.
In our frequent travels we have regularily stopped at Wal-Mart for an overnight stay. We do select those in safer areas, avoid those in others. We always end up shopping. We always check ahead of time on our "RVParky" app to see if parking is allowed.
We have never had an issue.