This is very difficult to answer. If you turn it into a working holiday and extend your stay you'll open up a lot more opportunities. Personally I wouldn't have the itinerary. You won't know until you get there whether or not you'll like a place, so budgeting for a month at a place to discover on arrival that you can't stand it throws the whole thing out of sync. My advice would be to go with the flow. Australia's a doddle to travel and you'll meet heaps of like minds en-route. Your adventure will unfold by itself. Guaranteed. That said if you're hell bent on having an itinerary, there're plenty of people on here that have travelled on fixed itineraries that can help you, someone will show soon enough.
I'd take the working holiday visa though, you never when you might need it, plus you can open further doors for more opportunities: by putting in 3 months work in rural farming, fruitpicking, etc you'll qualify for a second WHV and another shot at completing the itinerary you wouldn't have completed in your first year. In other words Australia's a very big place.

One thing's for sure, you'll have a great time..
