Isolation for Granite Surface Plate

I see from other threads that using a granite slab as a surface plate for a turntable is problematic. I am currently using a .75 inch thick slab as the top of a Zoethecus rack.  It is isolated from the rack by 4 Hudson 1.25" diameter silicone 20 duro bumpers. Can I do better with a different isolation feet? My wife is very happy with the way this setup looks, so I'd like not to replace the top shelf with a different material if I can avoid it.