I was going to say 2-3 for the group ride back down the track. Last month we were in a bit of a rush, as Dale and I had to get to work, and Debs had a hot gig to get to.
You could do it much quicker (I've done it the other way in less than three hours), but 2-3 will be fine with a generous second breakfast allowance in Barnie or Eppleby.
In other news, my mate says he got the last spot in the bunk, so anyone else who's coming will be camping.