It's a difficult location. Lily of the valley is a tough, shade-loving plant that spreads. You might also try some low-growing spring bulbs such as snowdrops and winter aconite. But you're real cjallenge is going to be getting plenty of organic matter in that soil to support plants that will already be hampered by the lack of any overhead sun. I don't have a lot of space.
Sugar Daddy is a heavy yielder and grows two feet.
I love plants and try to take care of them, but I'm only successful half the time. You're almost alwyas going to see them lose foliage and maybe droop or look pretty bad at some point. As to the ailing plant with oneleaf, that's your call. Depends on how attached you are to it and what it is. We have a new area we would like to plant a climbing plant to cover.