I would say you could easily weld some metal mudflap frames away from the tire that wouldn't take long to remove the flap on.
Look in the trailer section of a local farm store (not sure if those are close by or not) and you could find a metal license plate frame. Easily welded on so you don't have to do anything further or try and drill the bumper. I'm sure Cramazon might have some offerings as well and there is always zip ties! lol