I think this is by far the best way to reach JWs and wake them up. To go to a KH where nobody knows you and seem interested but raise questions either before or after the meeting. If it only helps one person, it's worth it.
Some may say it's sneaky etc... but no way can you talk to a brother on the ministry in a negative way. But going to a hall and pretending to want a study or know more. That way it's possible to seed some truths.