Public weighbridge in Perth region?

We are soon to head off around the country towing our 3 to 3.5 tonne off-road caravan and are anxious to know the total loaded weight and the ball weight when loaded (as well as the weight of the decked out 200 Series tow vehicle). We have only driven the unit back to Perth from the Sunshine Coast after purchase (second hand) last July, but it was not loaded for an extended trip. If anyone has knowledge of a public weighbridge in the Perth area, could you please provide location clues? We are aware of one public weighbridge in the Hazelmere area (near Midland Junction), but would appreciate other suggestions. Yellow Pages seems only to recognise makers of weighbridge equipment, rather than public facilities. Thanks.

Mike