From a purely engineering standpoint and understanding fasteners and clamping...

It seems to me that one solution would be to mount the posts through the playfield (underside electronics permitting). This would be the most economical solution as it would remove the torque from the top of the playfield to the bottom of the playfield during tightening, not to mention provide a more stable post over time. The neoprene washers address this issue in that the top of the washer absorbs the majority of the clamping torque as opposed to the top of the playfield. A nylon washer would probably be a better option imo.

I’m not defending sub standard processes and or coatings, just trying to find an intermediate solution to what seems to be a lot of bad playfields.

Just thinking out loud.

Not sure multiple layers over multiple layers is the answer here. Then again, at this point, I don’t think there would be any harm in trying anything. The crux of the issue is putting torque on a soft playfield.