Generally I believe that backscenes are good, unfortunately the shape, size and orientation of Morfa mean that only two and a bit sides are covered by them. A good proportion of the layout can be viewed from both inside the squished oval shape and from outside. Looking out on the bits devoid of backscene one has to filter out the rest of my playroom clutter, but looking in I hoped to be able to borrow the backscene from the far side of the layout. Take a look at the photo, it shows how the principle works.
The train is a foot or so away from the camera, the backscene about fourteen feet. In an ideal world I'd have used the whole height available to me, but practicalities forced a two foot high backscene, leading to the letterbox cropping of the shot. However the mind is a wonderful thing and when watching trains pass here, the white wall above the backscene fades out.