I haven't played around with hidden icons. But I know there's an icon cache. Also there's a registry setting that would allow you to increase the cache. It could be that if the icons are hidden they are not cached. But that's just conjecture on my part.
I know there's a tutorial on Windows Seven forum to increase the icon cache. Someone there should know about the hidden desktop icons. You may want to try the Customization subforum. Many of the customizers have had a lot of experience with explorer, desktop and limitations of the system. As example just changing the background color of the Explorer window is not trivial. One of the guys there made me an Aero Theme just to do it(I set the background Antique White to get rid of the "glare" when contrasted with the black desktop background used with fractal flames.)