The center moonlight is right over the top of the brace, right?
Here are some other ideas:
Eliminate the shadow by disconnecting or blocking the center moonlight
Place two other moonlights on either side of the brace.
I saved the best ideas for last

:
Use small mirrors to reflect the light around the brace.
Cut out the brace.

Please forgive me. There are a few reasons for my being a little crazy.
I've
kept my tanks in windows since I started the hobby so my tanks have
always had free moonlight.
Ordinary plug-in night lights on an extension cord are
cheap easy moonlights(see pic below)
Finally, I heard a guest expert
tell us that moonlights have not been shown to provide any value to our
tank inhabitants, though they do look really cool to the tank owner.

Aloha,
Mark

Edited by Mark Peterson - September 01 2013 at 4:46pm