Where is are some isolated camping spots in oregon?

I recently got a campervan and id like to try camping with it. Id prefer not to drive to far, maybe an hour and a half at most. I live in the portland metro area (tigard)... Id prefer someplace with a lake or a river and i emphasize that I want to be completely isolated. I dont want to see another soul durring my camping trip. I just want to be alone and to get away from it all. The last thing i want is for some homeless guy or a drunk guy or even a family to be anywhere near me. Somewhere I can play my music late, enjoy nature and not be bothered by anyone or even see anyone... Any suggestions?