I made a render test using the simple mat room. well that one is making sense and is quiet usable ( I like it so far ) 

the render time is ultra fast almost making me worried if it really does render, will have to play a little with it .

something I do not understand, there was always the Import Background feature, asking if you want to fit the window to the imported background, " It is Gone " took me a while to figure out that I need to use the simple material room! but the window will not automatically fit to the imported background, so this is a disadvantage when trying different backgrounds for sure and a big loss of time. But I might just not of found that Import background button jet, who knows ! 

Here a little render test with a simple drone Prop after applying the textures via simple room, lost most of the time getting that background right !