Coming to programming from a mathematics background, I don't have the experience to really take the above any further (I wish I did).
However, as for the original question, there is no image of the map belonging to the Bitmap class in rgss. Though, you can use ObjectSpace to pass all bitmaps; if you aren't using something based upon screen position, you can get the desired effect; though, that does leave a lot to be desired. Of course, you could, if you don't mind the tediousness, set something up that would capture all of the position data and pass that to; or do it incrementally. I don't think it would be difficult, just annoying, so probably not really worth it.
Obviously, if you're planning on replacing the screen with your own stuff, or something along those lines, that's not really all that helpful.