Don't sweat the small stuff. Here's some tips that will work better and look way better than a stack of washers.

Replace the fasteners holding the steering arms with high strength cap screws long enough to install a thick hardened flat washer and a nut. Purchase some high strength thread couplings. Not hardware store couplings -- the same grade or property class as the cap screws (G-5 or PC 8.8 min). These should be available through your local fastener supplier like Fastenall or from McMaster-Carr. Ensure that the couplers thread engagement are equal to the cap screw diameter but no more than half the thread so you have room to screw in high strength studs in the other end.

Measure to determine how much spacing you need to center the fenders over your tires and purchase aluminum spacers the correct length. Again, if you can't find them locally McMaster-Carr is a source. Purchase high strength studs long enough to thread into the couplers and spin a high strength stover type lock nut on to hold your fender brackets. Now you have a professional looking bracket that allows you to remove the fenders if you want without disturbing the steering arms. If you never ever want to remove the front fends then you can stick with the long cap screws but please consider using the correct length spacers and not a stack of ugly flat washers.

Now for the fender rubbing at full lock. Purchase Mustang steering rack spacers and use as many as necessary to limit the steering travel to prevent fender contact with the suspension or chassis. You can get these through Amazon and they're cheap enough you don't need to start thinking about making your own from PVC or some other backyard material.

BTW, what part of AZ are you located?