I like camping behind churches, often entering 'churches near me' on google maps when I roll into a small town, though they're usually on the outskirts as you ride in. I never ask and never stay if people are present because it becomes a big ordeal as we all wait for someone in charge to make the decision, followed by visiting time. I choose my site and swoop in at dusk, setting up my tent behind the church itself. I find they almost always have decent lawns (look for sprinkler heads) and there is usually a picnic table or pavilion along with a faucet and even an outside outlet for phone charging. Nine times out of ten I roll out in the morning with nobody the wiser. I've had church members and police pop in on me a few times, with never a problem. Rural churches are empty six nights a week, with rarely a phone number posted anyway, and seem to all have some brush or woods within walking distance for facilities. The same goes for volunteer fire departments- always empty, always a picnic table and faucet out back. Looking for a camping spot right at dusk is often the funnest part of the day; daylight is fading fast and the pressure to find your spot is on. Don't forget schools as a last resort- stay away from the buildings though. Remember, you're on a bicycle, probably the most harmless stranger one could meet.