Kel Tay

The Sky Panel is inside the room. I think Gabriel's director wants to see the background. (Details of What's outside the window) Yea, it could be use as a backlight too.

I would have done the same thing. Use your most strongest light unit as ur key; As tho as the motivation is from the window. Flag the side of the sky panel for spills. You could still slightly overexpose your exterior (at least you could still see details and the whites are not clipping too much) Use ND filters or nice ND gels (to cut n paste nicely at the window ) Hope this helps.

Get those 3M kitchen hooks. gentle to wallpaints. 3 on one end , and another 3 on the other end of the wall. Puncture ur black fabric (textile shop) with holes and then tie a simple knot into the hole and then tie to the hooks. make it stay as flat as possible