The national park on the northern side of the Burrum River is Woodgate Nat Park. It is as Terry says, a 4x4 road in, very loose, sandy track, crossed by several tree roots. It is a beautiful, quiet place, and as the sign at Childers suggests - it's where nature spends it's holidays.
The turn off to Woogate is at Childers on the Bruce H'way or from the north, there is a road direct from Bundaberg, about 60 klms from memory.
Entry to the national park is along the Walkers Point Rd at the southern end of Woodgate. You won't get lost, simply drive into Woodgate and turn right along The Esplanade (doesn't every place have an Esplanade !!!) :D
Be extremely careful swimming in the Burrum - I saw a monster white pointer in there, taking a mackeral - what an awesome sight !!!!
Kangaroos are the only pest you are likely to meet and yes, the ranger does holiday in there !!
Kinkuna Nat Park, on the road from Woodgate to Bunderberg, has plenty of 4x4 tracks, many more than Woodgate NP, but definately camp at Woodgate and take the 40 min drive to Kinkuna NP.
All the best