The difficulty of getting a backdrop that suits your particular layout especially if you are modelling an actual location is a common problem. I have found a way of getting such a backdrop.
1.You need to take overlapping photographs of the area you want to copy.
2. Download Microsoft ICE, a free program, which will stitch your photographs together giving a panoramic picture.
3. After you stitch your photographs, crop the image to reduce the height to that of your backboard, keeping it within scale.
4. Load your stitched picture onto a memory stick and go round your local High St colour printers and negotiate a deal suitable to you.
5. If you can, keep a large amount of sky in your picture. This allows you to reduce the size without losing any detail or if it is not big enough paint the top part of the backboard white/blue to simulate sky.
6. If you are competent with programs like photoshop etc. you can edit out unnecessary detail in your picture.
There are a sample of some of the photographs I took, cropped to edit out detail I did not want.
This is the result of the stitching program.
See Kirley Junction, in the Layout Section, to see how it has worked out for me so far.