So I think I've worked it out, the problem and perhaps, just perhaps, the solution.
The first problem was that I couldn't hang back, that's already been fixed by getting the hips further forward to give me a counterweight along with riding the reflex to come back up all the way down to the mat. Actually not ALL the way down but most of the way down, that becomes important later.
The second problem was that I couldn't come up without splaying my feet out to the sides. One way of overcoming that was to bend the knees quite deeply but that's not much of a solution
because it tends to result in you raising your heels or falling forward onto your knees, you replace one problem with another.
The possible solution
At first I thought it was just a case of getting the knees as far forward as possible, but I was finding that I was at my limit, I couldn't seem to push my knees any further forward and was still having to bounce off the wall a couple of times to come back up.
What I was missing was that it wasn't so much the knees I needed to get further forward as the hips. It was obvious and I've probably been told it a bunch of times. It's the same as the 'pelvis in space' thing from a while back when I was looking at the Press to handstand. There's a lot of weight in the pelvis, get that forward and you have your counterweight.
It's also what happens with the hang back. You push your hips forward allowing yourself to hang back, eventually you have to drop the last bit, on a video you'll notice that in that final drop your hips come back, they're no longer acting as a counterweight.
There's a Venki exercise that Boodiba was demonstrating a couple of days ago. She's in Urdhva Danurasana and keeps pushing herself forward. I liked that and tried doing it, first in UD and then after dropping back. It's a nice exercise but it wasn't enough, I couldn't seem to get my knees or hips any further forward, not enough to give me the counterweight to come up. That's when I realized why I splay my feet.
Check out one of the older videos where I come up with splayed feet, stop it just as I start to come up and you'll see that my hips are just ahead of my my heels, that's why I splay them and why I can't come up when I don't.
So I need to get my hips further forward but for some reason I can't seem to push them any further forward when down in UD.
The final part of the puzzle came this morning. I'd watched Susan's dropback again and she puts her hands on her hips to really push them forward.
I started to do that and then tried to get a little more by putting my hands just under my buttocks and pushing forward and up, kind of like at a 45 degree angle, that gives you a little more. While I was doing it I noticed something, a slight lift, a lightness. I tried to focus on that point and that action of moving them forward and up as I started to drop back.
I was pretty much hanging all the way, pushing forward and up, when I just floated back up to standing. This is on the video, it's like the spring action I've been talking about all week but lighter, kind of floaty, couldn't help laughing out loud.
The next thing I tried was after dropping back and then taking a step back closer to my hands thus bringing my hips further forward and higher up. You can see from the pictures it's a better position for coming back up, the hips are almost in line with the heels.
I did the same thing again, dropping back but kept my mind on that forward and up action at the hips all the way down, after landing.
I seemed to rock forward and on up onto my fingertips without trying and then I was back up. My feet splayed a little, but I think that was more out of habit than necessity (you can see in the picture on the right that my hips are in line with, if not slightly forward of, my hips, I don't need to splay them here). Usually I splay them further and push down hard on to the edges of my feet, here it was almost effortless.
I'd planned on doing another week of Bow sequence but I think I'm going to switch to the Vinyasa Krama Supine sequence for the week. Urdhava Danurasana comes into that sequence but before it does there's a lot of work on desk pose variations involving lifting the hips.
And if I'm wrong about this....well it's just something else eliminated.