Rear quarter repair

[stumpyjag 6]

Hi all

 

i am in the process of repairing the rear quarter bumper bracket area due to the usual rust problems. On one side the bottom edge of the rear quarter panel itself has rusted through as per diagram, but the rest of the panel is sound. 

 

What would be the standard body body shop repair for this. I have a matching piece from a donor car but seam welding it across the bottom edge seems very difficult so would I be better off spot welding them together from the inside then fill and blend where they join on the outside. 

 

Many thanks