Ranger,
Ledge Point has some good camping and fishing up in the sand dunes only an hour North of Perth. Sandycape is 200k north of Perth. Great spot but you would want 2 nights. there is actually plenty of bush campsites north of Jurien Bay.
South there is great camping and and around Dwellingup, Harvey, Waroona etc... Wellington Dam and Honeymoon pools is also brilliant spot. All only 1-1.5 hrs from Perth.