Here is the hard data as it is known at this time:
This tree a more consistent with the archaeological remains:
than this tree:
But there is a new theory put forth by different researchers about every other week.
Bottom line: The N mt haplogroup is distinct from D.
One has to remember that the landscape was far different when the D mt DNA crossing of the Pacific took place.
Due to rising sea levels most of the earliest data is going to be underwater off the coasts of South America.
Trace that landscape, trace the South American Ice Sheets,
and then you could start a search for inland migration routes.
Any N mt haplogroup who were coastal in Australia were washed away by impact mega-tsunamis in the mid 1400's and earlier.