As part of the illuminations I've also protected the running line with a colour light ground signal. It doesn't really notice much but I know its there.
Another reason for adding the frame is that I will be able to attach some black material to hide the legs, mine and the layouts.
I still have to add some building internal illumination and modify the main lighting rig to include a switch and some night light. I haven't decided how to do this yet, I might go xmas light shopping in Wilcos this lunchtime. They usually have strings of blue LEDs for not much money and they should do the job.