The best solution may be to use at the nightclub a separate router which is dedicated to your camera/iPad setup. I believe the camera (Eye-FI) and iPad (ShutterSnitch) can transfer just using the router's network -- no separate Internet connection required.
For emailing, you would need an Internet connection. This could be done by plugging the camera-dedicated router into the Comcast router via Ethernet. If the security is too high on the Comcast router, the emailing could also be done using an iPad with cellular service.
When I go out on paying gigs, I always bring my own router because 1) I don't want the hassle of configuring my equipment for the client's network, 2) I don't trust the client's network signal quality or amount of WiFi traffic, and 3) it makes troubleshooting much easier since I already know the equipment all works together.