I went to a semi truck repair and service for mudflaps. They replace mudflaps on a regular basis.
They have square tube (solid stock) mudflaps which sets into a square hangar in which you can lift out your flaps.
I cut down my semi flaps for closer to our size tires. Drilling the frame is tough (!) to fit hangars.
The square stock is extremely hard to cut & virtually impossible to bend (cold anyways).
Don't use stainless hardware unless you also use anti sieze thread prep. Stainless will gall the first time you thread together for a test fit and you are stuck with nuts/bolts that will not un-thread.
Ask me how I know this... ARGH.
I did not know to cut my flaps short (cut width only) and I tore them off in reverse lol.
Not an entirely successful project but when I get back to re-do this project I will use semi mudflaps again and fit differently...
Did I say stainless hardware sucks?!
I have not been pulled over.
My need for mudflaps is for keeping spray (dirty nasty spray) off my trailer. Or dirtbikes if I'm pulling my dirtbike trailer.
It wipes out everything.