When mounted basked onto my rear bike rack on commuter bike, I faced issue with mounting the light. Original clamp was good on seatpost but now would be obstructed by basket.
This adapter replaces mounting bracket. Made for 40 mm wires spacing, but can be easily adapted in model.
You will need also two M5 screws with large flange head + nuts and on M3+nut.
The spacer piece goes into the cavity under nut as on this light there are teeths used with spring loaded mounting for angle adjustment with original clamp.

Now happily using it for over a year.

Source CAD model:
https://cad.onshape.com/documents/b9ae8fe9429b4b651c29cafb/w/8837c2dc740f7d4204f4be54/e/53923c04e974c72d868494a8?renderMode=0&uiState=61a541b1fa33e35c4b6d7e60