The L shape was made precisely by furicks. But lacking of photos to illustrated the mounting location.
Personally, I found that the holder has the best orientation as it is the closest to the extruder. Hence, the levelling could cover most of the area of your platform.
Nonetheless, the mounting has to be side way and watch over from the side while pressing the jog mode.
Be very careful not to travel the -Y axis too much towards the front as the probe will extend, knock the dial and caught under the heated bed.
You have to unscrew the left extruder's fan and remove the spacer.
I printed it with 10% infill, 0.25 layer height. Place it like a L shape on the platform and I did use the support option for the slot.