I think you are going to have to apply the banner on a per-page/screen level if you want something like that without diving way into the guts of the framework. I would look at having a toolbar within the page’s header element to support what you are after.
Now from a UX point of view, I think it is a waste of pixels have a fixed company banner. You have a very small set of users of this app, and they know why they are using it. I am guessing the marketing department wants it…