What are the safety precautions taken by the members of the encampment to keep from being arrested?

From the text:

All we want to do is keep the knowledge we think we will need, intact and safe. We're not out to incite or anger anyone yet. For if we are destroyed, the knowledge is dead, perhaps for good. We are model citizens, in our own special way; we walk the old tracks, we lie in the hills at night, and the city people let us be. We're stopped and searched occasionally, but there's nothing on our persons to incriminate us. The organization is flexible, very loose, and fragmentary. Some of us have had plastic surgery on our faces and fingerprints.