Vibration Issues / Turntable Decisions

I agree with Willy, support the floor from underneath first . That is your problem. Stop the amount of deflection there . Except I would support it across the width just in front of where the equipment is and support that on either end right to ground . I’m betting when no one walks on the floor and your in your seat listening your happy with playback so it isn't your table and wall mounts are not always the ideal solution. If the floor has that much deflection and the wall isn't an outside wall without a door in it chances are with a floor that bouncy it will only reduce , not remove the problem completely. 

Fixing the deflection in the floor from underneath is not that difficult, its the choice that requires a bit more effort in a shorter time span physically ,but it is THE only choice that  removes the problem.
All others are band aids that somewhat work at varying degrees , and at differing degrees should you change the table or the rack.
A solid foundation will always give better results and cost less and take less time to do where access is available,  than the hours of work it takes to earn to save for an inflated , retail band aid to solve an easily solvable problem, not solved at all but just masked with band aids.
No brainer for me, a Saturday morning and its over, free to have any table, rack or speaker, stand mount or not with greater choice on design and function and cost.