there are 3 van parks to choose from
1 Woorim - This si a big park and not to bad although close to the surf beach it will be a 12-15min drive to launch the boat over the other side of the island so not my choice if you want to do some boating
2 Along the esplande is the other camp ground - it gets very packed but is in a prime spot like across the road from the boat ramp and shops etc..this would be very good for the boat is on calm side of island.
3 Across from sandstone point hotel just prior to the bridge is another van park, it has 2 boat ramps and the marina just there, although not tech on the island it is a good spot for boaties as there are 2 ramps and your in the water in secxonds without to many crowds , walk distance toi the best pub in the area too.
Camping
On the surf beach at woiorim - no good if you want to take the boat
Poverty point - ok if you have a very small boat but no good if you cant carry it sort of thing
My advice would be either van park 2 or 3 with 2 having a nice feel and good location along the esplanade you cant go wrong and then scope out the others for your next trip.
Hope that helps somewhat
jet