Stealth vaping can be done anywhere.
I did it right in front of the Ohio County Board of Health at a 2011 meeting when I was testifying against their proposed regulation to ban e-cigarette use in all workplaces and outdoors on all government and healthcare facility property.
Right before I did the stealth vaping, I told all members of the Board of Health (who sat about 10-12 feet away from me) and everyone else in the room to watch me very closely to see if they could tell whether or not I was vaping. Then I held an e-cig inside my hand (so they couldn't see it), raised it to my lips, inhaled for several seconds, held my breath for several seconds, and then exhaled (with no visible vapor).
Then I asked the Board of Health if any of them could tell whether or not I was using the e-cigarette. After none of them responded, I told them if they couldn't tell whether or not I was vaping (when I was holding an e-cigarette to my lips), that it would be impossible for employers to enforce an e-cigarette usage ban throughout their facilities, and that it would be impossible for health department inspectors going to enforce the regulation.