In reply to pff:
I wouldn't be happy with that. A regular cows tail I'd be happy with (moreso than a sling).
Never used one myself but this may be worth investigation:
http://www.animatedknots.com/purcell/
Though if you do go down the daisy path, some guys hang their ledges with Yates adjustable to make it easy to adjust the height, specifically Yates since they apparently make the strongest ones.