This is an extension of 733km of Scenic Rail Melbourne and of the basic 797km of Scenic Rail Victoria, both drawn in blue, with a major extension by 5,577km, drawn in red, to service all towns with 1,000 population with a radial, not grid network. Route length is the main cost as operating costs can be recovered at current fare rates.
QGIS with Open Street Map, JC July 2020 (Towns 500+ green, 1,000+ blue, 6,000+ red).
The rural network would cost $10M/km to build. Separate consideration of tourist investments would be warranted with better understanding of the cost structure.