Perhaps this would bring about some ideas. It will not simulate real wheel physics, but it copies wheels that are actually being simulated. In essence, it creates instances of the real wheels. I removed the bodies of these “instanced” wheels to keep it from rocketing forward at ludicrous vectors. As I learned before, you actually would need to go into coding and change the way the vehicle handler/ vehicle movement deals with each wheel.
You still will need those bones for the extra wheels, so just set up your vehicle the way you would normally, but instead of adding a 5th and 6th wheel in the blueprint defaults, just add this to your anim blueprint.