Unless only new I know of no airstrip at Iron knob pub or even close to it. Google earth does not show it either. What part of the lake do you need to get to? If north end Glendambo roadhouse used to have a dirt strip out back you could check that out. Unless your mate is going to collect you from the strip it is still a fair drive over dirt tracks to the lake so you will need a hire car to do it in. So that means probably Pt Augusta,Roxby Downs or Whyalla. Next problem you will have is getting a car from someone that will allow you to take it off road to a remote area.
As far as landing on the lake I wouldnt either. Even when dry they often have damp soft patches invisable from above. If you came to grief in one I suspect the insurance company would not be too keen to payout on that,and who could blame them.