Really wondering how the end point looks like. Should be great as you should indeed see Mt Cook. I hope I can come back one day (I live in the Netherlands). Cannot however see how busses could take this road. Or it should be 4×4 busses.
Have fun during the bike week! (and if you can register the gpx track that would be great, then we can add this route to the map!)
Small remark at my first post: Route starts at the Tasman Glacier Park.