Could I do custom pivot points for a 3D cube?

Hello Gdevelop forum!
I have a sprite based character in 3D. I accomplish this by flattening a 3D cube on the Z axis, and displaying his sprites on the front face of the cube. This way, I can move him in 3 dimensions, and have him rotate on 3 axis.

Now, 3D cubes always pivot around the top left corner of their front face. That’s also where their position is. I want my character to pivot around the middle of the sprite, at his feet.
Does someone got a solution?

Also, I know you can specify pivots with a 3D model, but this engine doesn’t support transparency for 3D models, so that wouldn’t work out.