Actually - I realised that a one way oneworld award there was 10 000 miles cheaper than an All Partners.

I'll issue my (paper ticket) RTW prior to departing MEL and have the itinerary with ticket number to show Japan's consulate for my visitor's visa, QF check in at MEL and passport control at NRT. Unfortunately there's no way immigration officials won't demand to see proof of onward travel as I'm on a Malaysian passport (and have been asked for proof 2 out of 2 times into KIX and NRT respectively).

The dummy return would be more secure though. Might call the consulate at some stage and see what they say.