Not sure if you want to carry any extra weight but my wife and I have used the "Camps" guide books for years and find them very accurate. The info in them may be available online. The Twelve Apostles is a tad out of your way and cycling on the great ocean road can be fraught with danger (crazy drivers, a few bends and chicane's and some think their a F1 driver). I would throw the bike on the train to Geelong, head out on the Hamilton hwy to Cressy, Cressy to Colac - Cobden - Port Campbell - Twelve Apostles an easy return day trip from Port Campbell, Port Campbell to Warrnambool via ocean road as it's a lot safer that end or shorter route via Boggy Creek rd (great pub on the way). From Warrny either head to Port Fairy and do the Hamilton rd at Killarny or head up the Caramut rd from Warrny to Penshurst - Dunkeld - Halls Gap... your are smack in the middle of gods country for climbing!!! I travel the above roads quite often and most are in better condition than the more major highways and offer some good choices for free camping.