If you will use HTML5 WEB app i think you can use a lil bit of javascript to help you with fullscreen ( only on interaction/click/touch - not easy to implement for all devices),
If you will use it as Hybrid, it will be packed with custom view so it will be fullscreen by default.
maybe you find something usefull here: github.com/gajus/orientationchangeend and github.com/gajus/scream
As i get it from C2 User Manual: Orientation is detected only in Hybrid apps no WEB... - maybe im wrong but it dont work for now for my web game..
My only problem is that FullScreen (Desktop - on Key Press) dont work on Internet Explorer and thats Shame, again i must go back to JavaScript..