How to replace SteamVR home enviornment

I want to create my own loadinscreen in UE4 with VR.
I created my own Loadingscreen level with streaming levels, but that doesn’t work because SteamVR pops up everytime i load in a stream level.

I can replace the SteamVR home loading splash screen, but I also want to replace the environment.
Right now it’s this ugly grey blue tpe colour, and i just want it to be bright white, how do I do this?

I know that users can replace steamVR homes in the Steam Workshop, so devs must be able to do it aswell right?