Where to take 12ft car topper

Hello everyone,
I am after some ideas on where I could take our 12 foot car topper later in the year eg. Sept. I am based in Brisbane and use my 5m boat in Moreton Bay but have used the car topper a fair bit in South Australia and southern NSW and Vic waters. I will already have a caravan on so the 5m won't be coming with us. I was thinking of heading North. I am not a big fan of freshwater fishing and prefer salt water creeks and estuaries. One option could Groper Creek which runs off the Burdekin near Home Hill. If anyone has any other hints please let me know.
Cheers,
Bill