The lack of responses may be due to your confusion of basic concepts. You said you're trying achieve "isolation" yet you've assembled a pile of mostly non-compliant materials that will provide little isolation to speak of. Either the goal or the materials must change. Which is it to be? We're so easily confused by randomness. ;)
Granite, mdf, wood buttons, spikes and spike cups are essentially non-compliant. Non-compliant materials and devices provide COUPLING, which is the precise opposite of ISOLATION.
Your massier items (granite, mdf, the TT itself) can contribute to isolation but ONLY if used to optimally mass-load some other compliant material or device (like springs, an air bladder or sorbothane).
Those rubber truck liners are probably compliant and might provide some isolation, but only if optimally mass-loaded. How thick is the rubber? What are its compression and rebound characteristics under various loads? With that information a mechanical engineer could estimate the optimal mass loading for greatest isolation at various frequencies. Without that information you're reduced to trial and error. You may end up with a Ford Focus on industrial-grade truck shocks (BOING!!!), or a 3/4 ton pickup on Ford Focus shocks (BONK!!!) or... you might get it just right. :)
What are you trying to isolate the TT from anyway? Forget the random pile of stuff. Identify your problems and goals and appropriate solutions will present themselves.
