My stealth camping setup consists of a tarp, foam pad and sleeping bag. I have a lot of different places (ie. in a long driveway, behind a commercial building and the most memorable was on a pier so I woke up looking out over the ocean). I am normally gone by 05:00 so I haven't had to answer awkward questions yet (ie. who are you and why are you on my property).

I lay the tarp on the ground and drive the bike over one edge, then flip the tarp over the bike and back along the ground. Throw the foam pad on the tarp beside the bike and quickly lace the ends shut. The weight of you and the bike secure the tarp and obviously no one can f with your bike as you are sleeping beside it. If it's cool out, the bike keeps you warm while you fall asleep, if it's hot, let the bike cool off before you setup the tarp. It takes less than 5 minutes to setup or teardown, has no parts to break and is easily replaced if something happens to the tarp. On a comfort scale, it is very low, on a cost/time/convenience scale it is hard to do better.