The backing challenge for night sequences offers a little more flexibility. All the camera will see out the window is what we want to see. A black backing allows the use of peanut lights on grip stands, a cat-out profile of the horizon (mounted at eye level, of course), or foreground greens. If an evening sky glow is desired, you might want to substitute a night-grey backing, in which case the horizon profile becomes mandatory. When tarping-in a real location to shoot day-for-night, it helps to effect to include some greens in the enclosed area. Don't forget additional off-camera space fr the gaffer's lamps.