Axle Vent

Not sure what the”v” you mention actually looks like but if it’s what I’m envisioning and way it’s mounted you could drill the bolt you have from the threaded end just up to the underside of the hex head, then cross drill it far enough below the underside of the head so it is covered by the “v”
File flats on the sides of the cross drilling 180° from each other or the full circumference. Akin to a custom made banjo bolt like used in brake lines on a caliper.