Hobie 18 is no good for what you want, no bouyancy up front and they break in half.
John Wright is the guy to talk to in SA about 5.8's http://www.nacra.com.au/classes email address is down the page.
Wont be over in Vic until 2010 Vic states. Tube post is cheap.

A Stingray could work out well with the Nationals at Victor but where would you find one?

Darryn