Hi. This may not help, but the SagaDive Flip Adapter takes the CMC without the extender ring without problem. The rear of the CMC just clears the port glass with fairly optimal close positioning. The newer style 67mm securing ring from SagaDive is needed as their original style one did obstruct the CMC.
See photos below.
Mark IMG_0245.JPG 55.15KB 13 downloads
IMG_0246.JPG 54.06KB 13 downloads