I did this for port and starboard.
I glued the first one on and used a spreader clamp to push it.
I decided to go with 2x 9mm doublers on each side.
|The doublers cut from scrap|
|spreader on port side|
|spreader on starboard side.|
After that was cured, I mixed up some wood flour filleting mix and filled in the sides that were rough. Then I glued in the second set of plates. While that was curing, I filleted that.
I may get some pictures and add a new post.
This should be plenty beefy for the motor mount.