Diagram and plan of action to create coffin

These are the original measurements of the crate that my dad managed to get from work. The plan to make it the shape that we want is as follows....

1. Make the box one plank narrower to give it a more coffin like shape.
2. Cut a hole in the end for leg room.
3. Make the whole thing stronger.

Note: to film from the side we can tip the whole thing because it is the same width.