after reading the title of this thread, i was originally going to say something flippant like "if you've been caught, then you haven't been camping stealthily", but i guss i won't.
i've been stealth camping since before there was a term for it. it's possible to catch a few hours sleep even in cities, in say the foot or so of space between a hedge and a wall. as per peterpan1, in late & out early, unobserved.
however, i`d like to share one approach to "stealth camping(?)" that has worked well for me many times here in japan. i do a lot of 36-hour rides where i ride through the first night and try to get home by the evening of the second day. here in japan, convenience stores are seldom far, and at one or three in the morning, it's nice to stop for a coffee and some pastry.
one night when i was tending to "fall asleep at the wheel" as it were, i hadn't been having any luck coming across a good location to camp. i stopped at a convenience store for a coffee & snack, and noticed that most of the cars parked around the outer parts of the parking lot had people snoozing in them. i thought, "what the hey!", went over to an out of the way spot behind a large truck, rolled out my sleeping pad and bag, set my watch alarm, and grabbed a couple of hours sleep, got up around 3 am or so, had a pastry and some hot coffee and continued on my way.
since then, i' availed myself many times. food, coffee, alcohol & restroom available at all times, and no one has ever bothered me, employees included.
well, japan is a pretty safe country and i don't think i would recommend it in most other places, but it definitely has its advantages here.