So I was concerned that where the passengers put their feet on the rear floor wasn’t solid enough. As you can see in the picture, the row of rivets I am pointing at is supposed to have a small brace under that thin piece of aluminum that they call the floor. The brace is only about half an inch deep. I didn’t feel like it would support enough weight. Or more accurately jumping and yelling and screaming kids. So I made the brace run all the way down to the bottom. So the new thicker brace that goes between the floor and the outer skin/bottom of the plane is 65mm tall. And then at the back bottom of that skin I put a piece of foam to fill the gap.
For better or worse it is definitely stronger now.