Looking a bit closer at your rig, I would recommend you try the following...
Remove all compliant (rubbery, soft, flexible) feet from between your plinth and your spiked support panel. Squishy feet are the enemy of best LP12 sound, IMHO. The lighter, harder and more rigid the connection to ground, the better!
This will maintain 100% rigidity from the plinth to ground, and help evacuate all noise and vibration from your deck - thereby improving the sound.
Here's a glimpse at our hot-rod. You can see the rock-solid BLACK DIAMOND racing cones threaded into the plinth... No squidgy feet here!
We have a 5-year-old tearing around the listening room - and a robot vacuum cleaner that nudges the rack during playback...
ALL WITH NO FOOTFALLS!