Here is a new progression for the SLDL that I did not have in my article The Deadlift: Teaching it and fixing it. It is a RFE (rear foot elevated) SLDL. I am almost embarrased that I have never thought of this. We catagorize (adopted from Mike Boyle) our single leg knee dominant exercises into two basic catigories:
Single leg supported - split squat, RFE Split Squat
Single leg unsupported- single leg squat
So this is basically where the idea came from. The RFE SLDL works great if the limiting factor tends to be more of a balance issue. Try it out.