The kobuki base by itself isn't going to drift, so it is sensible that the tilted inertia will cause the drift. Needless to say I'm able to hack my URDF with a weightless superstructure, but I wanted to deal with this in a far more practical way. I attempted all https://www.uk-exhibitionstands.co.uk/product/casonara-blimp-rectangle-360o-hanging-light-box-display-100m/