Great guys - good to see some interest early - lets hope it doesn't wane! ;P
Here's the proposed route:
http://goo.gl/maps/JMJQ I'm thinking meet centrally for this - probably from Big W carpark, Cumberland Park, about 10AM ish.
Take the back roads up past Windy Point for a look, through Crafers, then on to Strathalbyn Rd though Mylor, Echunga and Macclesfield.