You might want to look into taking Indian Pass Rd east off of Ogilby Rd. Its been a long long time since I was there but its about 15-20 miles of dirt road/washes to the river. I recall trails running off in various directions for good exploring but its easy to follow the main trail. Really nice camp spots at the river. One spot has a huge eddy that carries you up river about 100 yards puts you into the main flow and then pulls you back into the eddy for endless laps.

This time of year would be nice but water would be cold. Just a suggestion.
Tom