why make a new look for the tagcloud?
I've done unconventional things with the TagCloud module, like on this page where I use it only for the purpose of organizing words by alphabetical order, but I don't want to have certain words different colors or sizes. I simply applied the same thing here, but I don't quite know exactly how the conventional use for the TagCloud module is, so if you want to change it, go ahead.
EDIT: Oops; I seemed to have misunderstood you the first time, and so I see why a hidden tag is insufficient.
Well, there is a few of ways to do this: get rid of the search, place a How Do I Search link with the tagcloud as to make it obvious all the how do i's, or use some convoluted workaround with ListPages and dummy pages.