I wonder what is happening with Chicken of the VNC for you; it works for me. But SSVNC vnc viewer is much better than Chicken of the VNC of course.I can only connect by SSVNC, but not Chicken of the VNC, that's kinda weird. But that's enough.
BTW, since you are using SSVNC, you can click on Options -> Mode -> Terminal Services (tsvnc). Then enter "username@ip" in the "VNC Terminal Server" entry. When you then click on "Connect" it will 1) start SSH tunnel for you automatically and 2) start x11vnc for you automatically. You can save it in an ssvnc profile to Load whenever you want to use it.
Alternatively, you can select "Use SSH" and enter the x11vnc commandline you desire (i.e the one you mention in your post) in "Remote SSH Command".
In both cases you will need to supply a password or passphrase to ssh (either in terminal or in ssh gui prompt depending on your setup) to log in to the ubuntu machine. ssh-agent is handy for automating this.