We often stay overnight at Walmart stores on long trips. We don't need special RV parks, and can just sleep in our motorhome and get going the next morning.
We have a list of Walmarts that allow overnight parking, but: where to park? We are 40 feet plus the car under tow.
We used to just drive in and try to find a spot. That is a recipe for big trouble. Nowadays, we use the Google Maps application on our phone, and turn on "satellite" view. That way, we can preview the layout of the parking lot, and prepare to drive in and use what appear to be the best spots for our RV.