I used to have a listing of Wall Mart stores that showed those that did and did not allow overnight parking. It was out of date so I tossed it a few years ago. I found this listing online
http://www.allstays.com/c/wal-mart-locations.htm Does anyone have a better link?
I have stayed at a number of store lots over the years. Never had a glitch except when another camper full of young adults stayed up partying till the wee hours. The DW said I was probably more jealous than angry. We got up at around 0600 to leave and I fired up the generator around 0530. I doubt it woke any of them but it made me feel a bit better lol.