Turntable placement and isolation

FWIW, before you try anything elaborate (and expensive) you might try just placing a solid piece of wood on the carper (not on points) so the effect of the carper and its pad is spread over a wide surface and put your turntable on this and see what happens. I doubt that foot falls would be an issue - foot falls more often occur with suspended turntables which can just bounce like crazy. Personally I'd be more concerned with the effect of sound waves - bass notoriously live in corners and at wall boarders and this is where your turntable would be (I think).

The floor is the best place by far. Its very difficult to make a rack that is as good as the floor. I know. Mine was on the floor for years. When I finally developed a turntable rack better than the floor this is what it looks like https://systems.audiogon.com/systems/8367 Its a massive 750 lbs of solid cast concrete shelves, legs, and granite, with sand beds for the phono stage and turntable.

Mass is sort of the basis of a really good turntable rack. There's lots of different ways it can be done. You could more easily build a sand box and put that on top of any reasonably sturdy rack. 

However you do it, this is only the foundational first step. Next is springs. Because its all about vibration control. A lot of mass solves only a part of the problem because high mass physically cannot move a lot. It takes too much energy. It does however vibrate all by itself. Everything does. So what the mass does is eliminate large amplitude vibrations. Then springs are used to further reduce small amplitude vibrations. 

I've used the mass approach for decades and it works great. Recently I've started working with springs and they are great on the floor. So I have some ordered, hopefully they will be tuned to work well with the turntable, and will be able to let you know for sure. But for now, go with what we know for sure will work.

@newbee- Thanks for your feedback. I have a 2 inch thick maple butcher block which I would use to test the carpet scenario and report back. None of my components are going to be near the corners because of the exact reason that you mentioned. They are somewhat going to be close to the front wall. Components will start 18 inches away from the front wall at the center and they will be placed in two or max three rows ending near the speakers. The turntable position if on the floor would be on the third row after all components, starting from the front wall. So it will be centered between the two speakers and positioned slightly ahead of them. Thanks.