How to add second shader to gameobject as a mask for RenderWithShader

I need to make outline for selected object like in example: https://www.assetstore.unity3d.com/#/content/5145

It works fine, but here I have to create two shaders for my object with RenderType = "Funky", and without it. So if in my project 10 objects with different shaders, I need to create 10 shaders with RenderType = "Funky", and 10 shader without it.

How to avoid this extra work? I tried to use second material with shader RenderType = "Funky" for camera outline, but it overrides all color and texture settings of first meterial - like object has no first material.