Is there a pinch weld at the bottom edge of the belt line similar to the ADs? If so I would recommend a panel which eliminates this rust prone area.
I have repaired this area on an AD with a TIG welder, but it was a HUGE challenge. There is no longer a pinch weld there. I removed 1/2 of the height of the belt bulge above the pinch weld from lock pillar to lock pillar, and welded many, many small patch pieces to account for all of the compound curves in this part of the cab.
Carl