I don't think those 2 little panes of glass will have that big an impact. I would worry more about the weight of the light. Those braces are for lateral strength, not supporting weight. From the pictures it looks like they should reach the edges of your tank, no?
Your going to get reflection with whatever light you use, but with that light the way it is, someday its going to end up in the water when you bump it. You might have McGiver another to hold the light.
I can hang it from the ceiling
The centre brace is very sturdy
This is how strong it is my 3 year old son sat on this brace before and the light is now where near as heavy as him
This made me laugh. Think you have problems? My Oceanic 140 center brace is freaking 14" wide! LOL! Seriously though, just keep them clean. You will be fine. Hanging the light will look better too.