I used clear monofilament on this quilt
Agave Garden, the big reveal which was nothing but darks and brights. I encourage you to view the close up pics and tell me if you can see my ditching thread.
In your case I would use clear as opposed to smoke. Some people say the smoke has less sheen and is less visible when under direct harsh lighting (as is often used in show venues). In my experience the clear is fine for just about all applications.