The stave would have to be pretty straight to back with boo. You also need to prep the boo and get the back dead flat. You said you were a novice and this not something I would recommend to a novice. Do you have a decent belt sander?
As already said yew does not need backing or sapwood to become a bow. My inspiration many years back was a man called Ray Mears making a yew heartwood bow with another chap called Chris Boynton. It will be on youtube.