Question URP - How do you apply different post-processing per camera without using volumes?

I have a hacky solution for this but I'd appreciate some insight into what others are doing.

Here's my effect:

The images along the top are cameras rendering to render textures. Switching between them changes which one is rendering to the screen and which are rendering to RTs.

The static effect when switching is a post processing effect but must only apply to the cameras being switched. I can have custom render passes per camera so I'm using that.

Any thoughts and suggestions appreciated, and I'll share my (awful) solution when I can!