Backdrop 400m wide, Do-it-yourself: You can add your own picture. You must be able to manipulate pictures and know how to open and manipulate files in the trainz-folders (esp. a config.txt file). Gmax-knowledge is not necessary. See enclosed readme.txt.
Find it in scenery, name 'Backdrop'. Invisible from back. If you do not see it, rotate the board, then move/rotate the backdrop where you want it. For TRS2004, in TRS2006/7 with backdrop-function.