Your Envision tank might be the exact same dimensions as mine! Mine is not fully open on top, however. I have two cross braces, creating three distinct openings on top.
Like you, I made it clear on all four sides. I think you'll enjoy seeing into the tank when you are in the tank room. I know that I do.
I painted my fish room deep blue so it would not distract from the viewing from the front. You could also use a curtain behind the tank if you found looking through the tank to be distracting.