The room he's in right now is so small he's just slightly leaning against a desk and shelf. When I move into my new house and have a much bigger room I will probably do something along the lines of my original idea. Which would be some sort of third leg running from the floor, up between the robe and cape and attaching at the base of the neck or something. That way it wouldn't be seen, and you wouldn't have to cut into one of the boots or anything. No kind of disc under a foot would need to be visible either. Considering the robe and cape are just the right length, you could hide it pretty effectively I think, giving it the appearance of being free-standing.
Mine came out pretty well balanced. I look forward to actually "finishing" it though.