setting an additional SV_TARGET for Deferred

So after a bunch of research I'm a bit stumped on how to add an additional rendertarget in Unity.
The setup I'm looking for is, during the Gbuffer pass I store the local (object space) normal of the surface in SV_TARGET5, then via commandBuffer, before lighting I use this value in a compute shader.

Using CommandBuffer.SetRenderTargets won't work because unity reverts the values after your command buffer executes.
Using Graphics.SetRenderTarget does not work because unity sets the rendertargets after OnPreRender
Both these seem to only be intended for explicit Graphics.Draw calls, where I need this additional channel for all scene objects.
Using Camera.SetTargetBuffers does not work with deferred shading (https://issuetracker.unity3d.com/is...endertextures-dont-work-with-deferred-shading)

I can hypothetically write to this channel in my custom shaders, I can read from it in my compute shader, but the one thing I can't figure out is how to set it.

Is there a way to do this in unity's deferred?
I assume there's a way to do it in SRP's, but I really am trying to avoid opening that can of worms right now.

Thanks!
-Zach

 

Sorry if I wasn't clear, to ask the same question in far less words:
Is there any way to add an additional rendertarget to unity's deferred rendering pipeline?
Still have found no way to do this. I know it's possible technically, so I imagine there's some solution.

 

Can be done with SRP, can’t be done with the built in deferred.

 

Thanks, that's all I needed, guess I'll keep my duct tape solution for now until I have time to transfer over to SRP.