i tested it…  it works well!!! but it create an accoustic sound when you hit the mesh head…   i have kept the ring foam to avoid some retrig… and put some foam between the shell and the plastic ring and put 3 silent blocs to isolate the big plate to the cone plate support.
the only little problem is that the plastic ring is not very rigid…(the foam rigidifies a little bit)

this design works for me for a dual zone pad (piezo/piezo)(snare input on a td10) 

francois