I think you are out of luck. The way I understand the tagnavi.config stuff, only the track display can contain multiple tags, the upper level categories just filter on one tag entry at a time, and you cant display more. So you can have:
%artist%/%date%/%album%/%track%. %title%
or
%artist%/%date% - %album% - %track%. %title%
but not
%artist% - %date% - %album%/%track%. %title%