Have the object always attached 100% of the time in the actor file that is loaded itself, in this case linked to teh hand bone driving your rig, before export... . so if the camera is in inventory it will load a actor3d file that is has the camera in it, rather than fiddling about loading and attaching 2ndary 3d files.
Then map an opacity to the camera to make it invisible, when the camera is taken out change the textures on the camera. Even with stencil shads you should be able to make the camera 100% invisible.