How do I set up a GUI around multiple cameras?

So I have the set up in this image:


3 cameras; a perspective; top-down orthographic and left side in orthographic. I want to set up a GUI in the grey space around these cameras. [Some plain GUItexture as accent, some onscreen buttons, some live updating information about gameplay.] First attempt at doing this spawned a word in the middle of all the cameras; after turning the GUILayer off on all the cameras I attempted to make a 4th background camera existing only to render this new GUI; but that didn’t work (the perspective camera remained behind it for some reason). How do I make GUI outside of these camera areas work?

EDIT: Note that I also want the GUI to be able to popup over the other cameras (but certainly don’t want the repeating elements that come up via turning on all the GUI layers) best would be some type of alpha overlay to everything.

Change your camera settings:

Clear flags: Don’t clear.

Culling Mask: Only your GUI layer.

Projection: It’s easier to set up Ortho, but either works.

Depth: Lower numbers render first. If you want your GUI camera to render on top, make its depth higher than any other camera.