Troy,
This Baader brochure shows how their accessories change the distance. You can see how the stopper collar was intended to be removed to allow the MPCC to slide further into the focuser barrel in some applications. If you can find out the dimensions of the finetuning rings (OD and thread details it should be possible to machine a sleeve without the indent.
http://www.baader-planetarium.com/pdf/mpcc_e.pdf