Some years ago, when I lived in Flagstaff, Arizona, I answered a knock on the door of my house to find my buddy Bryan and a fellow I'm almost willing to swear was the backwoods character Gabby Johnson from Blazing Saddles. It seemed they'd been cut off by a wildfire from their unauthorized long-term camp at the head of Sycamore Canyon. Did I have any gear to loan them so they could squat elsewhere in the forest?

The two ended up living in one of my tents for a couple of months.

Several of my friends have been known to throw down a sleeping bag under the radar, often in a place or at a time that violates various regulations. But Bryan, a sometimes computer analyst who would work and live in town only long enough to top off his bank account before disappearing again into the wilderness, took it to a bit of an extreme. Technically, people are allowed to stay in many of the places he camped, but not for long enough to actually use the site as an address, as was his habit. It's hard to say whether he spent more time under a roof or under the sky.

Grand Canyon National Park is a common destination for stealth trips, since backpacking there requires permits that are restrictive as to time and location. Inspiration sometimes moves you at odd moments, especially when you're already camping on the north rim of the canyon on relatively unregulated Forest Service land. Since you generally have to apply for permits months ahead of time, a sudden yen for an overnight trip into the canyon itself is hard to satisfy on the spur of the moment—if you do things by the book.

Which we don't.

The key to getting away with stealth camping, especially when rangers are on the lookout for the likes of you, is keeping a low profile. When possible, my hiking partners and I limit ourselves to daypacks and what we can fit in them. That means little more than water, some cold food, and a very compact sleeping bag. It's actually excellent practice for shedding unnecessary junk and keeping the load light. And we're good at it: We've never gotten caught, and as far as I know none of our friends have either.

My wife and I actually had permits for one hike to Thunder River, for instance, but we ultimately didn't abide by them. Our destination was a spring that gushes from the north rim of the Grand Canyon before flowing all of a half-mile to the Colorado River. Not only is it a stunning site, but the cold water was a welcome relief when Wendy overheated on the trudge across Surprise Valley. (It's really frigging hot: Surprise!)

Our permitted camping area was a long hike from Thunder River, so we'd cached most of our gear before making the rest of the trip with minimal supplies. But by the time Wendy was cooled and recovered, the sun was setting and we had a long way to go to reach the tent. We stumbled along the trail by flashlight until the unmistakable maraca sound of annoyed rattlesnakes echoed through the dark around us. The reptiles had crept out to warm themselves on the heat the rocks had soaked up from the sun, and they didn't fancy serving as stepping stones for tardy hikers. So rather than further anger the venomous neighbors, we lay down right there to join the slumber party. We actually slept pretty well, after the adrenaline surge subsided.

For better-planned and better-equipped outings that include some need for shelter, I stuff a lightweight tarp and bug net in my pack. Forest green in color, the tarp blends into most situations—to the point where I've set it up and then walked right past it wondering where I put the thing. The next morning, the tarp and net pack down smaller than a loaf of bread. That makes the shelter unobtrusive both when set up and when you're doing your best to not look like you're searching for a place to make camp.

These skills aren't just helpful when you're planning to break the rules. They're useful when you don't know what your plans might be, or when you actually want to do things aboveboard but can't find anybody—say, on an Indian reservation—willing and authorized to do the paperwork. And sometimes you're just not entirely sure how friendly the locals might be, and don't care to find out the hard way.

As unnoticed as I might try to be, though, I never could beat my buddy Bryan for staying below the radar. It's hard to outdo a guy for whom a campsite was less a destination than a preferred abode.

"You carry too much crap," he told me once. And then he rolled up on the ground in a blanket and went to sleep.