Mock-up of how one would go about using swerve and still be able to climb the 6" step.
The wheels would be 3" in diameter, and the bottom of the upper wheel would be 6" off the ground.
Haven't quite worked out the gearbox, but it would most likely go on the other side, one gearbox and motor per wheel.
The cutout in the side plate would allow for the belt to bend in when you hit the step without hitting any metal.