Some modelers advised me to try out Sergent H0 knuckle couplers.
http://www.sergentengineering.com
I am not disappointed at all, they are not jackknifing, prototypical and finally easy to install. Mounting the tiny cast parts is a little challenge of surgery, but not so difficult in the end.
They are mounted on self made drawbars, 3D printed like the rest of the underframe. I will made this drawbars soon available for all my models.