If you haven't already gone .....
Do you really need showers for just a weekend trip ?
How far are you happy to travel ?
I just stayed at Paradise Beach (on 90 mile beach) for 9 days
Approx 3 hours from Melb, 30 min from Sale (take plenty of Mosquito Coils)
No showers, but modern drop toilets, tank water for washing up
Camp fires allowed and 90 miles of beach just over the sand dune.
Hot showers were available 2.5 km away at Golden Beach ($4 for 5 min).
This is just 1 of many Free or low cost National/Coastal/State Park camp areas in Vic
There are too many places to mention without narrowing down your requirements a bit more.http://www.parkweb.vic.gov.au/1process_ ... activity=5
Lists National & State Parks in Vic where camping is allowed (although there are several it fails to list)http://www.dse.vic.gov.au/DSE/nrenfor.n ... 123D7?open
Find State Forests with Camp Sites