I thought about a set of the Duraflap's to help protect the truck itself, but I already bought the WeatherTech's. I was very happy with the WT's on my 1500, but the WT's don't block as much on the 2500HD because it sits so much higher. Still a great product.
Surprisingly mine do not collect much snow or slop. I was fortunate that my hitch had a large hole on each side that I was able to bolt the angle iron to without having to modify the hitch in anyway. My first thought was to do like you asked and make something that would slide onto the hitch and be held in place by the hitch head.
Those of you who have made your own hitch mounted mud flaps, any tips for one used to keep heavy snow slop off a snowmobile trailer? Detailed pics would be great!
Thinking about using 1" square tube (overkill) due to the snow slop weight. Then notch it around the ball mount sleeve.
I suggest that you check out Towtector. It is made differently than the other "skirt" type of flaps. I towed a new 5th wheel 14,000 miles to Alaska and back and did not have any damage to the front of the trailer even after driving in some very rough roads. The back of my truck had very nice after-market small mudflaps also.