The kobuki base by yourself doesn't drift, so it is smart the tilted inertia leads to the drift. Needless to say I can hack my URDF with a weightless superstructure, but I needed to repair this in a more practical way. I tried all I'm able to think of, and https://www.uk-exhibitionstands.co.uk/product/pop-up-stand-3-x-2-bundle-straight/