Regarding isolation, I have access to various sheets of thick rubber and foam (neoprene, EPDM, silicone, etc) and may try that out. Is the goal of isolation under the feet only for foot steps and effects of bass?
IMO, with these materials, you will add bounce to the entire rig. I have tried many materials under my Linn TT and have found you need properly designed tweaks to prevent "footfall" and isolation from sound waves. Yes, the Linn is a suspension TT, but isolation applies to all TTs.
The Vibrapod system is a good cost effective way to isolate the TT or any component. Also, a major factor in isolation of a TT is preventing vibration thru the floor; eg, a floating floor, and the type of stand you are using. Sometimes you need to move the TT to a different place on the floor or wall mount it.
Enjoy that Technics.