Take a look at Hunter Douglas designer screen shades. They come in different degrees of sheerness allowing in more or less light.

You have a tub in front of a ground floor window.. A wide blade plantation shutter, Hunter Douglas, cakl a dealer ) on an inside mount , blades with no tilt bar, and set to a position that allows light, but obscures total visibility. In white, and the "faux" wood, smooth finish is just fine.

You arent' going to want to mess with a raise and lower of anything, nor totally obsure the window 24/7. Matters not how often you use the tub...........: )

• A Hunter Douglas Silhouette can do the exact same thing. Look at both options.