I don't think you should or shouldn't do anything. It's going to be what you want overall.
Like my Marquee for my Flynn's build. the Left side of it is black. I'm wondering if i shouldn't black that out completely, or give it that dark backlit glow. Really depends on what will look better.
At the end of the day you can make your marquee look however you want. Backlit, non-lit. Hell, i'm currently trying to figure out if i can use Neon or Nixie tubes for the marque on one of my projects. And thats definitely not to anyones standards or rules but my own.