Front rack brackets keep breaking

I’ve had the front bracket on this rack break on me 3 times. Each time, the bracket lasts a few months and eventually snaps; this time it was where it had to bend it to clear the straddle cable, but once it broke at the mounting bolt.

Anyone have ideas on how to prevent this? I know vibration is probably to blame, but I ride rough roads where vibration is inevitable. Maybe a different mounting strategy? Is there a different, beefier bracket I can use or fabricate?

I know this might be a better question for bike mechanics, but their moderation sucks ass. I figure lots of people here run front racks and might have ideas before I end up losing teeth.