My room is 13'-6" wide and 25' long.....the back 7' is taken up with stairs down and a small bar area, err, I mean equipment storage area...
When I started down the road of O.B. it was with Dannys V1.
I had them in my smallish living room ....14' x 17'....with vaulted ceilings.
They sat in there with big plush coaches and chairs (and really didnt have a right sounding as good as they did)
until my room was finished being built (former 1 car attached garage)
I placed them in the naked room with only 2 chairs and a coffee table as a gear stand.
I'll never forget just how crappy they sounded in that bare room....it was so bad I barely
I did a bunch of internet reading to see if absorption or diffusion was needed on the wall behind the
speakers. I came to the conclusion that I needed diffusion, some people REALLY disagreed with me.
A bunch of PMs later and I just stood my ground.
I built 4" absorption panels (Rockwool) and placed them on first reflection points on walls and ceilings.
I built corner traps, bass traps and even a panel over the diffusor to remove corner reflections.
My room is set up like yours(window on front wall behind speakers) I simply covered it with the panel and diffusor.
I'll never forget the dramatic change that came about using these treatments....I was always listening now.
My first front wall diffusor was a poly, my second was a QRD that I built from styrofoam coated with thinset.
The room was better than ever, I upgraded the V1s to Super Vs and was very happy.
What I'm getting at is I would consider covering the window with a poly or QRD of some kind.
Keep the bass traps (although I would make them bigger) and consider either absorption panels
or more diffusors(personal preference) at first reflection points.
I only give this advice because your room is so similar to mine, and your using the same Super Vs
that I had in my room for all those years, and I was/am VERY happy with the results.
P.S. you can just see a slip of the window in this pic.