I am going to assume that e-body door hinge replacement is the same between Cudas and Challengers. I have been able to replace my lower hinge on my Challenger doors without removing the door and the fender. I open the door so I can get my hand and wrench into the lower hinge area. I place a floor jack with a piece of 2x4 on the jack under the bottom rear of the door to support it. Take care not to damage the bottom door edge. The inside kick panel needs to be removed to access two of the bolts from inside which are the two I remove first. I then remove the two bolts from the door and the two remaining bolts that bolt the hinge to the body. Lift out the hinge. If you need additional room, remove the two lower bolts from the bottom of the fender's dogleg and you can slip a piece of 2x4 in there to hold the fender out. Note if any spacers fall out from those bolts. Some access (not as much) can also be achieved by removing the wheel and then the plastic guard that keeps mud and water from entering the hinge area from the wheel well. Work what is best for you. If the car fender is painted and aligned, try to avoid removing the fender. Just the way I've done mine in the past.
Terry W.