Usually ghost writing is done the other way around. A writer is hired by someone with an idea who is then paid to turn the idea into a manuscript or screenplay. Publishers have ghost writers that they usually work with when helping people to flesh out biographies. They also have a ton of editors who can write as well if lets say an author can't complete a project in a timely fashion or needs some help.
--- If your manuscript is any good and you don't wish to appear as author you simply market it as any writer does and when they sign you you select a pen name. Pen names utilized for several reasons, one is to protect the identity of the author, another is so that an author can work under multiple contracts of different genres without breaching any of them. If your manuscript sells well enough you can hire an actor to play your pen name and still maintain yet another level of anonymity.