Really I think the best solution would be to extend MCWS/Browse/Image to allow querying via something other than &id (which is hard to track down without the ability to traverse a hierarchy i.e. in the case of direct urls from theater view)
My personal preference would be &path; such as "audio\recent" or "playlists\recently imported"
and then have a few extra options from there:
The default would be as is; if the library item contains only one image return it, if it contains more than one return the "stacked" image.
alternatively supply &index=n; to return a single image with index n from the ordered list returned by the path
for example &path=audio\recent&index=0 would return the one most recently added audio item's cover art.
or
another parameter which returns a "wall" of cover art for all the child elements of the &path rather like the wall list style but as a single image.
What would also be pretty fantastic would be the ability to "redraw" the image, and optionally include some overlaid text; I'm thinking name, date imported, date played etc
although I fully expect this to be extremely painful to make configurable enough to be worthwhile, so would be happy enough with just the top ones