You can't really get from Wilbinga to Moore River. The council placed logs along the beach just before the moore river inlet, so it's not advisable to try to drive across this, nor is it advisable to drive on the beaches directly in front of the town.
While we were camping once, we tried heading north along the beach, and then inland from the inlet looking for a safe place to cross. We didn't get too far before we encountered a violent farmer who wouldn't let us pass, and then threatened to fetch his rifle
dare i say quite a few people try this route, but from my experience there's no way through. You just have to head north along wanneroo road, go into the township and then hit the beaches north of there.