...Update, and somewhat of a conclusion to this, finally:
Last Saturday, I got out the drill, mud flap, and finally got this taken care of. Was really a 2 minute job - take took some measurements, mark where holes should be, drill the 3 new holes, and mount the mud flap back like it was. Ended up using existing mud flap and just turning it 180 degrees and drilling new holes on the edge that used to be pointing down. Worked fine.
Not sure if they use different material for mud flaps on RVs vs larger trucks, but I had no issue whatsoever drilling the holes. No burning hot drill bit, no dulled drill bit, no melted rubber, none of that here. Drill bit went right through mud flap like butter and right out very easily. It seemed mud flaps were made from hard plastic more so than rubber, so was very easy.
I know exactly where, how I backed up over a curb and caused this. Was the first time backing the Motorhome in the driveway of new house just moved into last March. Over shot the driveway slightly and climbed the curb with the passenger side rear wheels. Only did that once, the first time, but once was enough. Will try very hard not to make that mistake again.