Pretty sure something similar could indeed be done with a BSS (I believe there's an example of a signal-level based 'loudness' function that does much of that). Trick would be the subharmonic generator (lots of room for fun experimentation/novel implementation).

Or... old dbx 120A or 510 (500-series module) 4800 looks like its control set is the same (two bands ~1/2 octave each, Subharmonic level, bass boost)