This is not a bad idea. I have an iPad in an Otterbox case and I use it for work. I am in the manufacturing business and I travel. When I am with a customer and working, I sometimes need both hands and I do not want to place my iPad down because it would be stolen for sure. So, I was thinking of some kind of holster or clip that would hang off your belt which would allow you to clip it to your body and let you use both hands. It's a temporary thing, it's not meant for you to walk around in, that would look ridiculous. I was thinking of something to place it in the small of your back.
In the Army, i use to place a manual or my paper pad down the small of my back while I worked on something having my hands free.
Or maybe a flap that could hang off your belt and hold the iPad sort of like a telecommunications soldier in the field who would hang the teletype gadget and morse code off a signal while on the move.!