On the parking lot directly in front of the Visitor Centre in Northcliffe they provide four free overnight parking spots. You can stay but you cannot put camping gear out (table, chairs). The lady in the Visitor Centre told us they had to fight long and hard for the permission from the Shire to provide the free camp, because the campground operators in the area were opposed to it.
There is a dump point (you get the key from the Visitor Centre), during the opening hours there are toilets, and the supermarket is just a few hundred metres along the road. Also, there are two pubs nearby.
On the parking lot of the Visitor Centre.
Muirillup Rd, Northcliffe WA 6262, Australien
GPS: lat -34.632791, lng 116.125440