On extremely steep descents I like to keep my hands in the drops and lower my ass behind the saddle so that my crotch is pretty close to the rear tire. The upper part of my body is sort of vertical but I'm extending my shoulders forward, my knees extremely bent and I'm basically squatting over the pedals.. This is surprisingly easy to do unless your setup has excessive reach. I run Thunder Burt micro knobbies and they very rarely lose traction in this scenario, but if they did I would simply step off the rear of the bike and grab the seatpost while transitioning to a squatting-sitting position on the ground. Obviously platform pedals make all this possible. I don't like clip-in pedals now.
On descending switchbacks it's also important to keep your center of gravity as low as possible, but you also have to have adequate weight on the front tire. A high handlebar setup won't work. You need substantial bar drop and your hands have to be in the drops. In this scenario I'm typically standing on the pedals with my lower stomach over the saddle, and my ass is hanging way out over the rear wheel. The upper part of my body is flat and parallel to the trail surface at saddle level.
So in my opinion your overall reach should allow you to get behind and lower than the saddle while keeping your hands in the drops. If you can master that squatting behind the saddle maneuver it'll allow you to go down insanely steep trails with a feeling of complete safety and control at very low speed.
Last edited by Clem von Jones; 12-02-21 at 10:02 PM.