The simplest answer is that there are no options, including ones you may not have found, that can reconfigure the MC Window in a way that would satisfy your requirements.
Nor would the MC Team consider implementing what you consider a "simple change" because that "simple change" would require the designing, programming and testing of a brand new skinning engine.
Like the OP, I too have always desired 2 Playing Now windows that were independent in order to show cover art in one half, and a visualization in the other. But just as the OP described, you
can set them to be different while the song is playing, but as soon as the next track begins, MC reverts both playing now tabs to be identical. However, the fact that MC
can have different layouts initially in each
Split View, indicates to me (admittedly not a programmer) a code adjustment that allows them to
continue to remain independent as tracks advance cannot be that difficult to do. Right?
Most media players show the play queue and currently playing item side-by-side (just as the OP desires). If MC provided this familiar layout by making the
Split Views independent, it might ease the transition of new users from other players, and thus more likely to convert an MC trial into a paid version. In addition,
Split View in general is far underutilized IMO. If JRiver enhanced
Split View with the above request and fixed its various glitches, that would put even more distance between MC and all other media players.
Hopefully Matt decides to work on the OP's request, and if he does, I have a couple more ideas that would really supercharge
Split View (if Matt is interested).
And to the OP… spectacular post with all the screenshots explicitly illustrating the issue. Nice work.