Frosted glass shower screens are excellent alternatives to plain old shower curtains. These look a lot cleaner and more sophisticated. They are permanently installed but they do not take up much space since the panels are thin but strong and durable. They are water-resistant so there should be no worries about the moisture. Cleaning is quick and easy with soap and water. It will look good as new for a long time.
Frosted panels may be better than clear ones for this type of application as they will provide a bit more privacy for the shower user. The image of the occupant will be blurred from the outside but light will still get inside without a problem. This is important when dealing with a space that is small by nature. You want to maximize illumination while containing the moisture inside.