Custom rack, isolation under platform vs component?

Hi all,

I build my own audio rack as pictured here:

I should have used wood that was thicker, as it is not super rigid. If I push on it, there is some wiggle. And if I apply some torque, there is some torsion. I believe if I bolt the platforms directly to the frame, and use the isolation under the components instead of the platform, the rack will be more rigid.

From your experience, do isolation feet work better under the platform, or the components?