You are too kind. I doubt I will ever attempt that route again, but if I do I will add an extra day, camping at Llangurig and attacking the monster climb early in the day. That way, you have all afternoon to freewheel from Cwmystwyth to Aberystwyth. Kim used the roads, which apparently include a few short, sharp climbs, but the Sustrans route, from Black Covert alongside the Ystwyth, is pretty flat.
I know the excellent Dave Lodwig attempted this as an overnight ride from Birmingham, but I think this could only realistically be achieved by bashing all the way along the A44, which has no appeal whatever for me.