I grew up in the Macedon Ranges and used to struggle with the same dilemma. After trying lots of spots without much luck, I found the river at Barwon Heads really good for light wind practice. Used to launch on the Ocean Grove side in the grassed areas off the main road.
Also tried Cairn Curran a couple of times and was good except for the algae. I remember a good day in light winds at Rye too, but was much further for me. Especially in the pre-cross-city freeway days.
Lots of good memories