HDPR Sample Skybox

I've been experimenting with shader writing in the HDR pipeline. I've implemented a custom sky following the guidelines found at https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@7.2/manual/Creating-a-Custom-Sky.html. I now want to implement a fog post fx shader similar to the builtin volumetric fog with skybox tint. The builtin one doesn't work for my purposes though, as I need planetary fog. My question is how I would go about sampling the skybox. I guess that you could have a separate camera, render the sky to a cubemap and then pass it to the post fx shader? but I'm wondering if there's a better way? Considering that the sky shader is used for reflections, I would guess that it's globally available somewhere?