Brass Plates in electric bass or guitar bridge + piezo.

I was thinking of adding mass to a cheapo bass bridge by routing out under the bridge a little and then putting some brass plate under it or some other material.

This would give the bass bridge more metal to add to sustain, I hypothesize. I also remember reading that acoustic guitar saddles push against the front of the bridge in the direction the strings are pulling. So, would this recessed bridge push against the edge of wood with the added plate and make a good contact equaling more sustain and vibrations through the body and back into the strings?

Could a piezo be added under this plate in it's own ressess to make a piezo acoustic type sound or would that be a bust? How could I mod a piezo onto it for a more acoustic type of sound? While I dislike the "piezo quack" from piezo pickups, it does add a very basic acoustic sound which can be a nice change.

Has anyone added weight to the bass bridge or used brass pins on an acoustic guitar with success? Has anyone tried this thing called a "fat finger" to the headstock to add sustain. Would making a thick brass plate and clamping it to the headstock until finding a good position and then embedding it with some bolts on the back of the headstock or a complete thick plate added, like the fathead? http://www.groovetubes.com/product.cfm?Product_ID=2130 Would one solution be better than the other, headstock or recessed under the bridge plate?