I have made another file that might be of use. First of all, it is not wise to stray too far from the origin (0/0/0). Best to stay close to the 'North pole area' of the main planet. So I copied your nodes into this setup, took a location on the main planet, and added a rather large crater. I don't think the small fake stones will really be visible on this high camera POV, so I disabled them. You don't need a compute terrain either (which renders faster).
I then rotated the camera, so you can get a view more or less like in your file. I don't know if this is what you need, but this is how I would do it.
I also added a 'sphere' of simple floating rocks (can be replaced by better rock objects), not very appropriate for Pluto, but just for the fun of it, and to show how that can be done.