13.13Minor 11 works beautifully

Now try:

Cm11

Cm7:

C E♭ G B♭

add D = 9

add F = 11

So:

C E♭ G B♭ D F

Here:

E♭ and F

are a whole step apart.

Much less problematic.

A practical voicing:

LH: C

RH: E♭ B♭ D F

or even:

E♭ B♭ F

This is a very characteristic modern/jazz sound.