Hi there mwheelerk,
You cannot add panes to a smartlist, but you can create a library view that is retricted to the contents of a smartlist.
It sounds as though you have your view there, under audio, so now you can modify that view to filter down to the subset of audio files you have applied in your smartlist.
Right click on your view and choose the customise option.
In the right pane, look for, and click on, 'set rules for file display'
Add rule > Playlists | Is any | <pick your smartlist from the drop down>
OK all the way out.
That's one way. Now any artists that fall into that smartlist will also appear in this view. Unless you need the smartlist for some other reason, it probably makes sense to move the rules into the 'set rules for file dispaly' area of the view, and delete the smartlist, if for no other reason than tidiness within your library.
You could also explore adding a pane to your view that is based on playlist group. Perhaps create a copy of the view (drag > drop on Audio > Choose copy from the resulting menu) to mess about with.
A couple of older threads you may, or may not, find useful noted below. The first relates to MC13, the second, MC17. Both still contain current information, with the v17 link, pretty much all applicable at this time.
http://yabb.jriver.com/interact/index.php?topic=52090.msg355419#msg355419http://yabb.jriver.com/interact/index.php?topic=68960.0-marko