I would like to access the launcher on my smaller notebook panel without wasting precious space. As space is not an issue on my external panel, there's no reason to autohide the launcher there.
Is there any way of setting up a hybrid launcher display/autohide mode, in which the autohide mode is active on one display only?
Short answer: no, no support for that.
You may try MyUnity, it has a few tweaks for launcher, but not what you want. And I guess even with serious hacking this may not be possible.