20 inch wheel issue...need a hand

[stepside83]

im wanting to put 20x8 inch wheels on my 83 stepside, with air ride, and if i do this the tire will hit the inner fender before i get the truck all the way down, and in pa we need inner fenders for inspection, ive seen pics of people using trailer fenders, i was wondering if any on had done this with the same size wheel could show pics or explain how to mount the trailer fender to inside of fender, my only other option is to run 18 inch wheels if i cant figure this out, thanks alot