Here is an idea I tested. Works at both assemblies and conventions. I have noticed at the last convention and at my last assembly that when I opened up my wifi setting, tons of hotspots came up for people tethering their tablets to their smart phones. Friends I know are always looking for open connections during the program to connect to for internet.
I got an idea and tested it at this assembly. I set my hotspot name to jwfacts.com. I looked on my tablet and sure enough it showed up for anyone that looks at their wifi list to connect to. Better yet, it covered the whole auditorium and I was able to see it all throughout the convention center.
Nothing they can do about it and no way to track it.
I even counted my time for it =D