Inverting text color over a guiTexture-textMesh? - android

I have a scene where i want to have my text change color based on the background color so it is readable. I tried using a textMesh but it is almost impossible to position this over a guiTexture and have my camera rotate while using screen to world point method. My current setup is using a textMesh and position it based on a guiTextures location on screen and then its guiLayer as z. But when i rotate the camera, it doesn't move with the view. My textMesh also appears as a faint pink rectangle rather than "hello world" text which makes me believe either android doesn't support it, or my shader is set up wrong. My textMesh shows up correctly as text in the play preview window.

Here is a link to a similar post i made where somebody suggested using a 3dtext object:

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