How to create reverse dynamic ssh port forwarding

I'm trying to set up an ssh tunnel layout where:

1. client A (not ssh-server enabled) initiates ssh connection to server S


2. socks server is opened on server S:yyyy that tunnels all data via client A


3. client B connects socks server on server S, and tcp data routes via client A to the Internet

A possible solution would be to add a proxy server on Client A (binded to localhost:xxxx), and then run on client A "ssh -R yyyy:localhost:xxxx Server". That would achieve the goal. But that's not as clean as using just ssh.

Is it possible to achieve this with just the ssh client on A and ssh-server on S? it's like reverse-dynamic-port-forwarding on ssh - creating "ssh -D" from A to S, and then somehow setup on this tunnel a second tunnel of "ssh -D" from S to A. Somewhat confusing, and not sure if possible.