for this particular application I can live with this ripple voltage. At Vout=13 V I have 500 m V of ripple, additional capacitor does not help reducing ripple, it only prolong ripple period. I assume I could reduce ripple by choosing inductor with more inductance, as you wrote, but it is already now physically very big ... MP9943A is not an option, I need higher output current.
Ripple of 500 mV goes dramatically down when Iout>1 A, which is quite high current considering that I have I out max 5 A. If you will find another approach to reduce ripple voltage in the future, let me know.
As mentioned, I Will not change anything for this application, but in general I'm not happy with such high ripple voltage.