Inner sill repair

Hi All
My first post here. A family member 2002 k11 only 20000 miles from new started with a smallhole in o/s rear inner sill. 20210613_112241.jpg
After a tap round with the hammer this was the next result.

20211120_144630.jpg 20211120_144637.jpg
Then cut out best I could. 20211120_152024.jpg
The final welded result. 20211120_173738.jpg

Looking through the holes you can see the boxing section is rusting. The outer sills are fine.