VR mainline layout. dual mainline station, yard, eh? I know a fellow with a accurately scaled model of Wallan circa 1974 as his home layout, that takes up 27 x 10 feet!
An 8 x 4 footer will have boring looking return curves at each end, but ever long container wagons will make it around okay. Here are some random layout ideas:http://www.cke1st.com/m_train2.htm
As for Victorian locations on double track, you don't have many to pick from out in the country: out from Melbourne to Geelong, Bendigo or Moe.