Pharan, thanks for the reply.
I know this can be done with another camera that only capture the Spine gameObject layer and renders it to a RenderTexture. We already do this for our background layer. I haven't been able to find a better solution this is probably what I'll do.
08 Sep 2017, 18:04
I thought I would add a small update to this thread. I found a video that shows a pretty clean approach to using the separate camera captures to a texture technique.
Shaders Case Study - Brawl Stars: Toon Shading - YouTube
There is a couple of minor drawbacks. You are doing 2 draws instead of 1. There is also a slight loss in quality when comparing the texture to the original. However, for us this has only been noticeable when doing a side by side comparison.