The car park you mentioned (and in Firiebob's reply) is the one we launch from - next dirt car park north of Salt
We've had up to 6 out on slalom gear - I think fastest is Norts with about 34 knots (actually Slowy was faster but he doesnt count).

It is a bit sporadic that anyone will show up though, Safety Bay, Woodmans or Point Walter will normally take preference if they have potential in the forecast conditions.