gack, that is an awkward place for a window. 2 feet above the tub?
Going with the opaque glass theme, how about replacing the current window with an acrylic "glass" block window?
We put one in our dining room and it lets in all the light, but provides great privacy.
It took some getting used to. I would walk out in my chonies in the morning and quickly stop, thinking a plain glass window was wide open. I had Wally go right up to the window, like a couple of inches away, and told him to wave his arms, walk around in front of it, while I went outside.
Even when I stood right up against the window, I couldn't make him out, there was no definate outline at all. There were just some random blobs of color and not many of them at that, which wouldn't suggest a girl in the shower at all. Whoever saw it wouldn't know if she was in the shower, or standing a couple of feet away at the sink, if at all.