Ideal World

What I think I was hoping for was some small, good quality, figure-eight
PiP microphone that I could mount alongside the Videomic, so that I
could add some stereo ambience to what I had already, in post
production.  The resultant pair would be able to fit in my day-sac, and
would have reasonable wind protection.

Following a little research I now realize that producing a quality
figure-eight microphone is not at all easy, and nothing like this
appears to exist.