The Kobuki base by yourself does not drift, so it makes sense the tilted inertia results in the drift. Certainly I'm able to hack my URDF by using a weightless superstructure, but I planned to fix this in a more real looking way. I attempted all I'm able to think https://www.uk-exhibitionstands.co.uk/product-category/hanging-towers-seating/blimp-hanging-hanging/