Fossil Creek: Video
The hike to the 20 footer is totally worth it, and like it has already been said, just paddle the rest of the way out, it'd be a bit quicker and less work too. The last "Falls" is called 'Powerhouse', there is a left line and right line, with a small island in the middle that makes the split for the lines. Both go. In the video (~13:05 minutes) I end up goin backwards down the Left side, not intentional, but it all worked out.
We made the trip down there this past November, the weekend before Thangsgiving weekend, and it was just natural flows, ~ 50 or so cfs.
I'm sure it'd be even more fun with some extra water.
If you're going to stick it out there, don't be afraid to get it cut off.