Though I’d add some notes of my experience. Last year I did the SF by entering at Holland Lake and then down Gordon Cr but this year I decided to try Lodgepole Cr and over Youngs Pass. I’ll just go in logical order from trailhead to takeout.
First: No shade and very ashy. I found the pass to be completely burned (~95%) from the trailhead all the way to the South Fork (confluence of Danaher and Youngs.). There is very little shade and it was difficult to keep the ash and dust from covering everything in camp. So expect to put some effort into keeping cool and clean while not on the river.
Second: Blowdowns. After going over Youngs pass and descending past the cabin site (only the log foundation remains) there was a section of blowdowns that was limited to about a hundred yards. Not terribly hard to go around or climb over, which ever you choose. It looks massive but really it’s nothing.
Third: Log jams: Between Youngs Falls and the confluence of Youngs and Danaher there were about half dozen or so log jams. Between Y&D confluence and Big Prairie there were only two big log jams (a third one when the flow starts to drop). None of the log jams that I experience were in any kind of pinch spot that would require frantic evasive maneuvers. I should mention that I floated from the base of Youngs falls to the Mid-creek takeout.
Fourth: I didn’t find any issues after Big Prairie.
Fifth: The Gorge. There is room to portage in the gorge before the foot/stock bridge at Meadow cr. but not after it. In low water (last year) it took me a whole day to float/portage the three miles to the packers roost (horse corral at Meadow cr.) and climb out, so I skipped it this year. (Honestly, the hydraulics were so powerful before I hit mid-creek this year that I wussed out by the time I got there.) Also, (west side only) there is no trail up from the river to the stock corral/parking area and it is a hell of a bushwhack through extremely thick growth up a very steep embankment. There is no rock climbing but you will be clawing your way from the rivers edge to the top, in growth that is so thick that you can’t see the ground under your feet. Also the river speeds up as you approach the last takeout spot and you cannot see the bridge until it’s too late, so you better dam well know your spot to get out.