kResolutionShowAll without black borders?

Is it possibly to use setDesignResolutionSize( 800, 480, kResolutionShowAll ) and showing something else instead of black borders?

If I run my game with a resolution of 900x480 I will get 50 black pixels to the left and to the right.
This will happen even if I have a big background lets say 1024x1024.

My plan is to have a dummy background outside the design resolution and all impotent things (like buttons) inside it.

But whatever I try my big background refuse to render outside the design resolution.

I have also tried to use kResolutionNoBorder and specifying a wider design resolution then what is actually needed, but this will not get the correct behavior if I run the game on a squareier device.
Example:
Lets sat I set the design resolution to 900x480.

  1. If I run on a device with that aspect (900x480) everything works fine (my dummy background render nicely on the sides and I have my 800x400 area in the middle).
  2. If I run on a device with the aspect (800x480) it will cut 50 pixels to the right and 50 pixels to the left and I will have my important middle area left.
  3. BUT if I run on a taller aspect (800x580) what I want now is 50 pixels over and under my middle area, but this will not happen.

Any idea how to get this right?