Live bait is always best however I have had some luck with white / silvery soft plastics in the past. Barra are night prowlers and its much easier to land them around night fall as their waking up and everything else is settling down.
As for locations I'd check up where it's stocked possibly? I caught mine out in Emerald in the Nogoa River here: https://maps.google.com/maps?q=-23.5...m&z=16&iwloc=A
That being said Emerald is a fair way away from you (and usually me) so whilst I'd recommend it for a trip for the family if you are willing, I can't really help you with places closer to Caloundra.
Sooner the better though, everything slows down a tad in the cooler months.
Good luck!