A purpose built track at torrens island has been rumoured, which sparked a bit of interest, but nothing concrete yet.
and as for "i would be more than happy to help build and upkeep the track as long as we were able to use it on a regular basis", it is far far more complex than that, your looking at state government funding, qualified people to design and build the track, insurance costs, etc etc. I see your drive, but i the stadium cash is going into the new oval at this stage, if you wanted to put in a proposal youd be waiting until at least 2012 before you could even drive on the new track. Best outcome in my opinion is to get more frequent use out of either Port Gawler or Mallala.