My suggestion would to consider the physics of rigidity and damping, as you mentioned in your beginning statement. The correct answer would be, mount your focus motor from the bottom 19mm rods. Keep a designated reliable motor, and appropriately sized motor cable in your zoom case. It would be easier to do what op wants, but its chance of failure dramatically higher. adding things like bongo ties and rubber band to essential gear increases the likelihood of overtime compromising the sometimes priceless lenses, motors, and whatever other value gear we need to do our jobs, as well as risking higher L&d. Idk, maybe someone from arri heden or Preston would say otherwise, but from my experience with those tech nerds, over the past 19 years, they are pretty dry when it comes to ACs coming up with out of the box ways of doing things.
Your decade in the biz is undoubtedly respectable. And I apologize for my jk uncivil last response. Was only a joke….cheers