Multiple cameras 2D sprite with 3D character depth sorting?

I have two camera, one for sprite and one for 3D object. I want to know if it is possible to make both cameras use the same sorting order (as in renderer.sortingOrder)? I have tried setting both camera.depth to the same values but still one eclipse another completely (ignoring sortingOrder and sortingLayer). I know that it is possible to achieve this with one camera, but since I used a customized perspective projection for this 3D object, so I need two separate cameras.

Thank you.