Surprised that a musicman cannot get the sounds you want especially for funk & R'n'B. Mark King used one on one of his albums, then there is Louis Johnson, the late Bernard Edwards and many more.
I put a pair of Alembic Activator P/J pu's with twin vols, bass & treble on a 1983 japanese Squier(now donated to my son) and it transformed the sound completely!
Gone was the passive dull thud and lack lustre top, loads of bass and hi fi treble with all the stuff in between.
I own a Mark King standard with the humbucker pu's and filters with 2 position Q switches, the higher alembics have variable Q controls, single coil pu's(plus dummy humcanceller) and they give a totally different sound although it took me the best part of six months to get to grips with the filters.
There are some great threads in this section explaining how they work although they are complicated in the theory but using ones ears(as we all do) should get you there.
The main difference with bass, middle & treble on your m/man and the filters is subtlety, only slight adjusting of the controls produces huge tonal variations.
I guess the guys at Alembic didn't bother producing a replacement pu for the musicman as they must have thought that it was good enough already!!
Anyway hope you fine what you are looking for