Your getting way to particular here. If it looks level then that's close enough. I usually balance so the nose is down just a tad. This really isn't rocket science. And to answer your question about the horiz stab - yes that would be a good reference for level. I wouldn't be to wild about adding the weight of even a light weight level to the stab while I was checking for balance. I think you'd be better off just eye balling it.