Modular sliding bathroom
In order to maximum the efficiency of your bathroom, many ideas might have been carried out. The previous spacesaver is a perfect one. But I bet you will like this one. It is actually a modular bathroom and all the modules can be on its own rack. So you have not need to worry about lacking space.
What you should do is to slide the modules, including the shower, toilet, sink and cabinet, totally depending on your favor.