Be sure to download the list of "no park Walmarts" and save yourself the hassle of getting turned away at one. We parked overnight in a number of WM on our 57 night trip last Fall and never saw anyone with a Pop Up that was extended. Doesn't mean you can't try it. The most comfortable experience is when there are other RV'ers present. When we were the only one, it felt alittle strange but we did it anyway and never had any trouble. We never asked permission as we didn't want to bother management. We parked out of the way, and made a purchase and placed the receipt on the dashboard! Crime can happen anywhere, but I felt most at risk when we parked at WM. You're a "sitting duck" out there especially if you're the only RV in the lot.