As for the eastern Platform a quick coat of asphalt and you have a temporary surface long enough for the show. A shelter, I suggested a Marque as was used for the temporary stop.
The article suggests that the show shuttle will be running.
If the show shuttle must run as a train and not just a higher frequency 21W to the Goodwood Road entrance, to me it looks like the best option would be to get the same old staging contractor to set up the temporary platform for one last time. Further down to the south after the future Wayville station, around the spot where it would stop to change ends and near the back access gate as used previously.
It's a clean and simple solution that would get the job done without getting in the way of the station construction continuing. The eventual opening of the fully constructed station could well be held up by over three weeks - a week for rushing something into place, a week of no work during the Show and then for at least a week after the Show as the rush job has to be dug up and done properly.
The main thing the department needs to do is have security deny all their communications staff entry to the building when they arrive at work today, they are so obviously incompetent it would be better if they were all fired. The Advertiser story is the usual garbage, but it does show quite nicely the mess of mixed messages going on here with three second-hand sources (the unnamed source quoted yesterday, the City of Unley and the RAHS) reporting completely different understandings of where things are at, with the end result being that the department has absolutely no capability to make sure a consistent message is being pushed out in all media formats and to all external agencies who have an interest. If the communications staff have lost their ability to control the message then there's no point having them there.
If they had competent communications officers who proactively pushed out honest updates on their website and to the media, there would have been no need for the confusion reported by the Advertiser. People are going to be far less offended by there being delays in the various works around Adelaide than they are by the government attempting to hope they won't notice. This is a case where somebody needs to take ownership of the issue, kick some heads and get things back on track.