How do I turn off Bluetooth Discoverable mode on an iPad 3

I am going to a security conference soon where the participants pride themselves on breaking into electronic devices brought to the conference. I use a Bluetooth keyboard on my iPad and therefore can not turn Bluetooth off. How can make the iPad non-discoverable? If I do need to add another device in the furture I know the name of my device as well as the mac so I am not concerned with it publishing its availablitity to the world. I am aware this is a "benifit" for most of the world to ease connection to other devices, but in these groups it is very much a detriment.