There's only one van park now and that's Sugar Bowl Tourist Park. Ph. 07 4126 1521 It's usually full of backapckers but they are fairly tame and easy on the eye ...
It's on hte Bruce Hwy so easy to stop and park.
There's another one about ten mins out called Childers Tourist park Ph 07 4126 1371. It's set amongst a bush setting if you prefer that but you will need to drive into Childers whenever you want stocking up etc. It's not on the Bruce Hwy so maybe not what you are looking for.
As Gibbo has said, there's apple Tree Creek which is a free camp just north of Childers. I think there is a 20hr limit on your stay there.
HTH..
Scol.