Over the last 24 months daily SA gas gen has not exceeded 1,145MW (27482MWhrs) - so that might be a practical max they can deploy. Remember gas fired units were not made for 24/7 constant running.
Demand on Adelaide hot days can reach twice the above gas gen numbers. Late afternoon-evenings are the critical time. Imports can peak at about 600MW or 14,400 MWhrs for a day.
Wind as ya know varies - but in a period of light wind that can last days - the system will strain to meet demand. Fact. So keeping the grid charged up is a bit of a lottery in SA. Building a second connector to Vic will help but SA should pay for or arrange that themselves.
This NemWatch gizmo gives you a neat summary of who is generating what across Oz at 5 min intervals. Imports are shown in the State where generated - not where purchased. You see at a glance - it is coal that runs Oz.
http://reneweconomy.com.au/nem-watch