The problem with GarGraves and Atlas is not the track, it's the mounting surface. You would have better luck replacing the Styrofoam with rigid foam like this, but I don't know about the noise level. I've only seen 1" thick sheets here, so it would take 4 to get to 4". I tried Styrofoam with RealTrax and then moved to the extruded foam. Noise wasn't much better because it was on a raised frame and not on a plywood base, table or floor, It was never by the tree, so I moved it to the garage for the holidays. 
I don't know what you're layout looks like, but you might try covering the foam with soundboard. Many people use it here in place of Homasote on top of plywood, but it should work the same on foam. It would have to be attached to the foam, with glue or maybe double-sided carpet tape, but it would hold nails to keep the GarGraves track in place. It's only $12.50/sheet and might be worth a shot. It is messy to cut, but you only cut it once, right? It's also heavier than foam.
