What is the etiquette when staying at Walmart pkg lots

What a great discussion...
Just remember, anyplace (other than a highway rest area) that you overnight, you are a guest at the owner's convenience. Treat it that way. If you can come and go and they have nothing to show for it but the receipts of your purchases, that is how it should be. We do this a lot as we are travelers and not so much campers. Your coach can be a magic carpet to all those places that you read about in National Geographic as a kid.

Matt