There is the ‘to_proposed’ parameter which moves the spindle farther of the mount which gives more room for the bolt. By the way I think it’s better to put a nut not the bolt on the front and have the bolt from the back. It won’t require much room.
And one more important parameter is ‘tool_coverage’. Set it to .15 and the ‘neck’ of the spindle mount will be narrower.
See attached my tries to produce the mount for you.
Another option is to use zip ties. 🙂