How much access do you have to that captive nut? You may be surprised to see that only a few bolts need loosened to pull fender back a little. It will pivot and move due to the many "joints" in the front clip. Maybe just the main body mount on drivers side front, front bumper loose and the fender-to-cab bolts. The inner fender can stay attached to fender. The whole left side of clip may move forward some. Just need enough to bend the captive metal back and get to the actual nut and spray and loosen.
Option: Take off door, make a support mandrel to floor so that when hammering/drilling/reaming is done to pin hole, the load is carried by floor, not hinge.
