There are all manner of aftermarket sheet metal repair sections, shaped like the original areas to be "patched", for most common rusted out areas, on most all the trucks covered by Stovebolt.com. Referred to as patch panels. They are relatively inexpensive. They can be trimmed down to be as small as necessary. You cut out the bad rust on the truck and weld these in place. You need to search the internet on this subject. Hundreds of pics and videos. Examples below:
EyebrowHinge area on "A" pillar