Instead of using the expensive acrylic sheets take a look at the 2×4′ fluorescent covers. I saw one for less than $11 that looked good. There was one for around $8 also, but seemed like it would break easier. Might could also put some rigid insulation or Styrofoam on the inside of the frame to cut down more of the noise.
My legs are 5″ & have the bottom of the flex feet bolted down to a 1x6x6″ wood block & have that clamped & it is pretty solid. I might have to rethink how I am doing that with these panels in place though. Not sure I have enough room for the clamps with the panels there.
I just checked the table & I do have enough room to use the clamps on the corner blocks & the middle pegboard. I am liking this design.