Back in my Dragon days, the massive genoa aboard was controlled via a floating jib fairlead and not via a track. I’ve often wondered how this might work on a fifteen. Here are some notes from David Williamson, on how he has gone about it….
In the Jib Sheeting detail pic.
Spectra slip-loop to attach tapered jib sheet.
Graduation reference marks on splash board as a visual jib sheeting reference.
Shroud adjuster (cut down as I saw in a pic of Vials/Turner boat in Hong Kong)
-Couldn’t help myself, these are also bolted on permanently and are part of the hull weight.
David
The Flying Fifteen Blog 
Useful photo for working out the system for the new genoa – how is the elastic attached to the block? looks very tidy but detail is behind the block so can’t be sure how its attached