Update: I noticed that the connecting rods are not quite parallel. This creates a tilt error on the effector. Since the sensor is not in the center, the error multiplies in the measurement result. That's why I not recomment to use a probe like this on a kossel.

This touchless probe sensor mount does not steal any printing space. The probe just hangs between the rod ends and nothing is touching at all at a printing radius of 116 mm with the Kossel Plus. The Mount is for a sensor with a diameter of 12mm. For calibration I just touched the Ground with Nozzle on a paper and screwed the sensor down until the signal LED has been lightened. No Z offset needed anymore.
Y Offset is just -36mm on my Printer with standard effektor. I decided to fix the sensor with some superglue in the right position but there is no need for..
With my sensor is a little soldered current needed. If you know a Probe, there`s no extra electronic needed, please post a comment below.

Yes

0,2

50%

I used lines as supports and it printed like a charm.