I've worked in multiple national parks so I actually know what I'm talking about.
Every National Park is drastically different with its approach to illegal campers. Generally, the only obstacle to stealth camping successfully is figuring out where to leave your car. Some parks allow overnight parking so they'll only bust you if they see you crawling out of your sleeping bag in the morning. Other parks will give a warning/ticket to any car parked overnight unless you're displaying a permit for backcountry camping. In my park, you'd probably have a 50/50 chance of getting a warning or a ticket if you were busted doing this.
The obvious solution is to leave your car in a National Forest lot, or in town (many parks have free shuttles from town into the park).
Once on the trail, you just have to avoid backcountry rangers who will ask you for your camping permit. Honestly your odds of encountering one of these guys is very low, but all the same it's best to minimize your time on trail, or have an alibi ready.
Wherever you camp, make sure it's well off the trail. Check your map to make sure. Don't leave any trash or light a fire, kthx.
>>2498979Based, please come do it in my park.