Mixing on an iPad works in SOME scenarios, but when you need to do lots of stuff and fast, a physical surface wins hands down.
In your case, wanting to have a 'mix' you can hear from a not ideal location presents some challenges. While you could put some speakers or headphones that give you the main mix, the problem is that you don't hear how the ROOM sounds. If you have something loud on stage that could end up too loud in the room since you can't hear it at the mix location.
What you could do is set up a room mic and listen to that to determine the mix. It would take a little getting used to to get things dialed in, but probably is going to be the most accurate if you've got to sit at the console in a non ideal space.
