I've always replaced the minimum necessary, most times just buying some body metal from a local supplier is best - the 12" patch would be easier to deal with than a whole skin, providing you've got welding down or know someone to do it
with the door off the cab you can get a peek in the hinge hole, and any deterioration will be evident, then you decide how much to open it up - I've cut out the hinge [front] face of doors, that works to fix the area and is easier to weld back without as much bodywork
Bill
