Improving Engine for space and planet landscapes

Hello I am developing my own engine and I would try improve UE4 and I would like implement double precision coordinate, relative camera, planet landscape, procedurals elements and maybe streaming rooms at UE4. I am looking to UE4 source code but it is complex web of code therefore I can need help for orientation in it. I would like for polished implementation. And I would like for use in my project and next projects for other developers.