I don't believe any of the solutions that offer mirroring to a computer will work directly across to another network. But you could use one of the meeting solutions (GoToMeeting, etc) or other systems that allow you to share your computer screen with another computer. That might work, though I haven't tested it with any of the mirroring solutions
I think perhaps you missed my point. No, you can't use GoToMeeting or any other such system to share your iPad's screen directly. You need to use one of the solutions such as Reflector to mirror your iPad's screen to your computer. Then you use one of the screen sharing solutions to share your computer's screen with the computer on the other network.