Had the same predicament as you - where next especially given the diverse weather you can get in Oz! How about WA? Perth and the surrounding areas, drive down into wine country around Margaret River and then drive North along all the beaches toward Broome? Dont know if you will make it as far as Broome but from what l have researched there are many beautiful beaches and great opportunities for snorkelling & diving - and l know you like to fish so bound to be fishing opportunities too! And you already have the camper van experience so you are practically an expert!
Good luck and let me know what you come up with cos l might steal some of your ideas!
PS looks like a duplicate post so l will delete the other one!
Just come back to Sydney Garry. I owe you a few beers and it would be a pleasure to share another drink.
Try an outback experience, rent a 4wd or just in a regular car along the stuart highway. For me, that was part of australia, which I really can not find anywhere else.
Cities, beaches, wine areas, all nice, but nothing special after a while.