make camera background cull everything

I attached a screen shot of my game running at a resolution where theres extra space at the top and bottom. How do i make it so that anywhere the camera background is exposed, it will render above any gameobject?
Really not sure how to accomplish this considering my background texture has to be above the background camera, but all the objects i want to cull are above the background texture so how can i make them go behind the camera background…36886-capture.png

The Dimension(Aspect Ratio) of your play field(BG Texture) seems to be constant. So download the image below, import it into Unity, in it’s import settings set Alpha Is Transparency to true, place this on a Quad with a Transparent Shader. Now stretch the Quad until your play field(BG Texture) fits perfectly in the transparent window of the texture.

Now hopefully this will mask the borders regardless of the display aspect ratio.