The whole point of CameraRange is that nothing beyond the far range is rendered. Fogged objects are still rendered, just displayed in the fog color.
As for the "how big" question, I would recommend against placing objects 1,000,000 units from the origin. Your camera range of 50,000 is already way big. By that far away from the origin things start getting flaky because of inaccuracies in numerical values. To implement a huge space sim you shouldn't be literally placing objects relative to each other as per real life, you should be using tricks to make the scene appear larger than it really is. Tricks like LOD and using texture imposters for distant objects. This is the idea with a skybox after all; instead of literally placing some mountains in the distance, you put pictures of mountains all around the player. Think of a Hollywood set.
As for the "how big" question, I would recommend against placing objects 1,000,000 units from the origin. Your camera range of 50,000 is already way big. By that far away from the origin things start getting flaky because of inaccuracies in numerical values. To implement a huge space sim you shouldn't be literally placing objects relative to each other as per real life, you should be using tricks to make the scene appear larger than it really is. Tricks like LOD and using texture imposters for distant objects. This is the idea with a skybox after all; instead of literally placing some mountains in the distance, you put pictures of mountains all around the player. Think of a Hollywood set.