You can see it there under what remains of the footwell panel. This panel will be remade and replaced also. The outrigger does have a hole in the bottom from new but is not supposed to have a big hole in the top !!
Special tools are needed for this job, namely a 4.5" grinder and a welding machine.
This 130 amp Supermig from Sealey should be fine on 2mm mild steel.
Stay tuned for more rock n roll :)