Curve physics on cube

I am making a test project that i plan to have everything, so i will not forgot some things i REALLY need to remember. In one of it’s scenes, i am plannig to make tree cubes aligned, and the cube in the middle will serve as a bridge. But it just doesn’t looks nice being a cube. So, i was imagining if it was possible to add some sort of physics so when the character is in it, it curves and shake a little so it appears to be a real wooden bridge.I am talking about a shaking and movement physics, not to make a curved cube. Here’s the example scene.

Have you tried adding joints and other physics components?