OK, just some thoughts.
You use your iPad to control GP and you want to show some picture to the audience, right?
So you could minimize GP and show a big picture on your monitor to the audience.
There are several solutions for that.
You could use scripting to start an external program, for example powerpoint.
Or you use the song/lyrics windpow to show an image.
Or you could use special VJ software (I am using GrandVJ) to show picture or videos.
Via a virtual Midi Cable you can synchronize such clips to Gig Performer.
Or you could try this plugin:
Video showing how to play videos in Gig Performer using VidPlayVST
You have the start global play and then with a Midi Note you can start the video.
By the way: Are you using a Beamer to show the picture to the audience?