I have a friend who could not find exact matches to oem fender skirts for his Crusader. He ended up getting some generic ones with the appropriate measurements. They worked fine and look good.
Have you tried a dealer with a good parts dept?
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder