Welcome to the tweakend!

I tried the inner tube thing back in the 90s. I found it just about impossible to balance components where the center of mass was significantly off center.

 Very easy, you need to "think out of the square", you buy an inner tube that is smaller, 2/3rd’s the size of the plinth it’s under and locate it more to be under the heavier section of the load. Inner tube is far better at isolating than thick rubber balls.

Cheers George

Just got my Amazon order. Picked up some nice some cans of
Raquetteballs, a dozen Sushi dipping dishes, and a couple of excellent quality maple cutting boards. Let the games begin!

Even better would have been "half inflated" scooter iner tubes under the bread board/s. Thinner rubber and air as the isolator.
https://www.walmart.com/search/?query=scooter%20inner%20tubes

Cheers George