Is there a way to put metadata on another page (a page other than the page viewed)? Call to it with include? Is there any reason to do this other than obscuring from prying eyes? Effects on SEO?
No I don't think this is possible. I think you would only be able to include it in a separate file for server side code. Then once a browser opens the page, it automatically adds the include file contents to the page's code. Really this isn't worth doing anyway. 5 - 10 years ago there may have been more reason to hide meta data. These days it is not that important for rankings. So it is fine if your competitors see it.