Alternative for 3D Skybox in HDRP

Does anyone know of an alternative to camera stacking when using a 3D skybox as a backdrop for scenes in HDRP? For example, an alternative to creating a small planet and moon next to a "background" camera to use as the backdrop to a main camera which is viewing the main scene with ships, stations, etc, thus creating the look of a very large scale planet as the backdrop to the scene.

This is easy to do in Built-in and URP using camera stacking. But what about HDRP? (Considering the graphics compositor is not recommended for games)?

 

I couldn't figure out an optimized way to do it with multiple cameras/compositor/etc. I just ended up using one camera and huuuuuge planets moved far far away at the visual size I wanted, and then set the camera's far clip plane past that. In built-in, this would've caused shadow imprecision problems, but in HDRP it's not an issue, possibly due to camera-relative rendering.

I also keep a fixed distance between the planet and the camera whenever the camera moves. I thought that translating the planets so far away from the origin should introduce floating point imprecision, but interestingly it's actually not noticeable at all.

Not sure, but perhaps there's a way to do it with Custom Passes if you don't want to go through this route.

Btw, check out this thread for more techniques:
https://forum.unity.com/threads/render-far-objects-without-increasing-the-clipping-plane.929103/

 

Another solution could be to use your directional lights as they also share a cookie atlas for mapping.

So long as you turn off the shadows for all but one of them, you can add circular shapes that fit in the Celestial Body > Surface Texture slot.
Your Texture atlas will fill fast so be cautious of the pre-computed memory cost

You can then set the angular diameter higher to show a larger planet in the sky and set the LUX depending on how you want to emulate distance and light contribution ( for a night scene for example.)

Depending on your project you could even bake this down into an HDRI for more performance gains