4-5 years ago I talked to a guy in a Class C who said he had been out about 6 weeks and had only spent 2 nights in a campground. He was spending every night in Walmart parking lots. I asked him where he resupplied water and he said a lot of the larger gas stations/truck stops had water. I asked him where he dumped sewer. He said at night he would run his sewer hose in a ditch, empty his gray and black tanks then leave before daylight.
Remember this when Walmarting - If you don't support the local campgrounds then don't expect them to be there the next time you're thru the area and need a campground. If enough people Walmart the campground owners might not still be in business. You're driving a $100,000+ rig and set up. Cough up the $30 to support our hobby.