If you look at a map of Queensland, Australia, Frazer Island stretches up the coast, sea horse-shaped, from just north of Noosa, to the Rum town of Bundaberg.
About half way up, is Hervey Bay, the point from which most people embark for the island. but look closer.
Down at the sea horse's tail is a spit of land called inskip point, and about 5 miles south of that, the beach town of Rainbow Beach. While Hervey Bay to Frazer is a forty minute ferry ride, the same trip from Rainbow Beach is about 15 minutes (10 minutes driving up the beach and five more on the ferry).
From there it is a clean run up the eastern beach of the island to Central Station, in the heart of the island. About a 30 minute drive, but fun.
The southern section of the island tends toward scrub rather than rainforest, so you probably won't want to dally too much on the way, but there are a few creeks, and as an alternative route to the island it can save you about 60 minutes. (Hervey Bay is about 60 minutes north of Rainbow Beach by highway).
You will need a permit to drive and camp.