Hi Martyn,
I agree that in ideal circumstances (if that’s the right way to describe an inverted Wayfarer!) the jib sheets could be the answer.
Sometimes this isn’t possible though. For example, if sailing with continuous sheets, and particularly if also using a partly or fully reefed genoa, there won’t (I imagine) be enough slack sheet to reach far enough over the hull to be much use.
The sheets are also less accessible than a purpose-made line, assuming inboard positioning of the leads, which seems to be fairly standard now.
In view of the loads that the shrouds are subject to at other times I don’t personally feel anxious about connecting righting lines there, but it would be interesting to hear other opinions on this.