OK kids, I just had an idea, a twist on incidental witnessing. Go to restaurants and other public venues near the convention site and strike up friendly conversations with them on their off time. Pretend to be interested in what they are doing and their little "revival", you would have to be careful to avoid any witness vernacular so as not to tip them off, use words like church and sermon, you get the idea.
Pland seeds by using all of the methods they use, ask questions, draw them out, they will think THEY are incidental witnessing.
Deb