there's USFS camping between 6 mile put in and douglas creek campground. there are designated campsites in the wilderness before the doug creek campground, then there's the campground. from just downstream of doug creek to bennett peak, there's a lot of private land with short parcels of public mixed in. if you camp at doug creek or just above it, it's an easy day the next day to bennett peak where there is an established BLM campground. you can camp on some of the public between doug creek and bennett peak, but some of it is less than desirable...it's almost all private land between bennett peak and the next take out downstream - treasure island. same goes for the stretch between treasure island and saratoga. i've never floated below saratoga, so i can't tell you about that.
before you plan to camp on private land, a lot of those big ranches are heavily patrolled, and the fine for trespassing is $1k. make sure you see the blue sign designating public land before you decide to camp.
By the waterside I will lay my head.
Listen to the river sing sweet songs to rock my soul.