I did ours myself. Not easy to do it all depends on what else is in the area. I used the supporting frame for the grey tank on one side and that flap is shorter. On the other side I had to fabricate a frame and bolting it to whatever existing framing I could find. That flap is longer. No one but me knows that because it is not apparent unless one gets down and specifically looks at it. If anyone really wants to do that they are welcome to do so.
I did not mess with the frame and do not recommend you do that. Rather than drill into the frame I would suggest making a "pinch" bracket like the rear track bar add ons do. I would post pics but I just find posting them on this forum to be very difficult for me to do, and since every installation is peculiar to that coach would not likely help much anyway.
It also depends on what you are using for mud flaps. I just removed the across the back rubber flap and cut it into mud flaps and used the angle iron that it was mounted with for framing. I think I may have bought one short bit of angle iron to finish things up. If you do not have a across the back flap to work with you will have to buy commercial flaps and be prepared to modify (cut) them.
The best offer I can make you is that if you send me or post some pics of the area behind your wheels perhaps I can offer suggestions and then via email send you pics of my installation. Good luck.
