How to specify a depthSlice of Camera's targetTexture?

I am using a RenderTexture as a Tex2DArray. To render to an element in that array, you need to use SetRenderTarget to specify your desired element’s index as the parameter depthSlice. But to render using a camera, you can only set the targetTexture of it. How do I specify which element I want to render into, when using a camera’s targetTextrue as a Tex2DArray? (FYI, the reason why I am obsessed with camera is that I also want to use GPU instancing, which can only be achieved with a camera.)

Good news! It seems the Command Buffer’s verision of DrawMeshInstanced does not require a camera and with Graphics.ExcuteCommandBuffer, this method looks promising.