Video -I need a white/grey background expanded to hide the set

I need an expert editor to edit various video clips to expand the white cove we filmed on to appear stretched out for the whole background screen to be white/grey as opposed to just 80% of the screen.
the shot is a wide of a host and set items on screen. the images will tell the picture of what we are trying to achieve for all of these video clips. previous editor was having system difficulty to covert the clips. Please send all clips back in ProRes 422 to maintain image quality. There are 32 clips of 1-30 seconds long

Notes:
His method was to crop out the centre where most action was happening, and use content aware fill to generate the rest of the image. His issue came down to processing speed. On the shorter clip (Number 1) he was able to achieve this without much issue. But the second clip "AA-Wide01142010" took him 5 hours to reach 10% when analysing. Happy for you to use a different method as long as quality is not compromised.