I've been working away with solos, as described above, and have found a small problem which I haven't been able to work around.

Solos generated and frozen in this way are often truncated - missing a few lead-in notes before the first chord of the solo, or dying in mid-phrase at the end.

It doesn't seem to be possible to get the solos generated only for the range of bars I've selected - if there's a solo track at all it will be generated for the whole piece, and then selectively suppressed according to Bar Settings.