Dew my brackets also twisted out of the door, also on a buddys Cougar. So we welded the original brackets to a flat piece of metal and repainted it. Almost looks factory. The brackets were not even in the same place either, from the factory.
My new brackets are pretty close to factory position: need clearance for the struts.
The metal was 4"x8"
Now the problem is the door is 95% styrofoam. It hard to tell during the daylight, but the very left and right sides (top to bottom) have wood. At night open your outside kitchen door and look at the very left and right sides. You can see the there must be a 1"x4" running top to bottom. With this pic that puts it on the 3.5" mark to the outside.
Next time I would use a 3"x8" and keep it flush with the long "L" side of the bracket and use 6-8 screws. I'm only using 4 of the 8 and have not had any problems
(installed 1 year ago), probably because of the bigger footprint.