Hi Alastair,
Sorry for the delay in the post. On a job today and arranged the returns as the pics show. Always oversailing the return boards and securing with a toe board the width of the platform then continuing the toe boarding from the last inside board will pin down the end of the return fleet which I'm sure you've already done or something similar. May take a minute more in the planning but the results look great and no extra unit needed.
Let me know what you think, cheers.