Clay,
I dont have a real (attached) plate, but I do use the light blue 3mm foam sheets when I take pics of flies in the vise . I just prop it against the bobbin cradle. That is unless I have a BLUE damesl fly.
I think it was one of the Fly Tying: The Anglers Art episiodes where they were demonstrating different colors with different flies. Unless you only tie the same color patterns, at least 2 colors (light and dark) are reccomended.