Absolutely. I can't speak for North Carolina, unfortunately. In the western states, Bureau of Land Management (BLM) lands are a great source of small "primitive" desert campgrounds plus pretty much unlimited boondocking anywhere you care to camp, except where otherwise posted. (Watch out for cow pies, though-- most of these lands are grazed.
) Once you identify your region, the BLM website should direct you to the website of the nearest district office. It should list camping opportunities. For further info just phone or email them and ask to speak to their recreation specialist.
National Park campgrounds generally have some vegetation screening between sites, unless it's real desert country. The popular parks can get crowded during high season, though. Ditto for what Dexterpix said about US Forest Service campgrounds.
State and Canadian provincial parks are a real mixture, from more developed to decently wild. It may take some research to learn which is which.
Once you've got your general destination area figured out, you can ask around, including on this site, about less developed places to camp.
In terms of lengthy boondocking, we travel with a generator, full water tank, gas and water jerry cans, and we try to get water and battery conservation down to a science. Where available, we'd use the campground restroom/pit toilet facilities during the day to save water.
We've been 'streaming with some frequency now for 9 years, including several trips of 6 weeks out, and have never stayed in a Walmart parking lot.