I'm not saying it isn't tough, but I did it in granny gear the whole way and took lots of breaks. It took me the whole day, but I did it. I had just started riding, and it was hard. I think it would be a whole lot easier now. It actually isn't as bad as it sounds, I promise.
Good luck and I would love to hear how it went. My BF and I would have loved to join you if we weren't in Victoria this weekend.