Sleeping lofts are a great way to maximise space. I really like this cabin with it's one legged ladder but I don't know that I think much of that 'safety rail'. Do you like it? Not the rail, silly - the cabin and sleeping loft!
In the book Little House on a Small Planet there is an exercise. They suggest to go to each room in your house and write down all the things you do in that room. Post a note at the doorway and when you think of something else add it to the list. After a week or so you should have a pretty good idea about how you use your living space.