From the bridge on Greenwood Road at Hendy Woods, we took off hiking downstream to suss out the possibilities of a 15 mile through hike to Paul Demmick Park on Highway 128.
It was fun, wading through places that were chest deep, seeing waterfowl, frogs, turtles, and even a Bald Eagle. We trekked down about 5 miles, then beginning to feel beat up, and the day wearing on, we decided to head back up stream to the truck.
The total out-and-back mileage was about 10 miles, plus we hiked a logging road too far and that cost us an extra 1/2 mile. The hiking wasn't hard, but as we have found doing these river hikes/wades, it wears you out faster then normal trail hiking.
Conclusion: A 15 mile through hike is definitely doable with a bivy half way in behind the mountain. We will let someone a lot younger and more fit tackle the distance in a single day.