I've done it. We had about 10 or 12 weeks though. But you could still see heaps in 3-4 weeks. We got a train pass and took trains everywhere. We hired a car once or twice to go to more remote areas and it was scary driving! Way preferred the trains which were fantastic, you can enjoy scenary along the way or read or sleep etc. We just booked somewhere to stay online a few days in advance and made up our itinerary as we went along It was great.