Actually, most PRS owners I know (and I know a LOT) would dig having piezos. The big problem is making irreversible mods since they tend to be a shot to the head when it comes to resale.
I believe GraphTech makes saddles that willl fit on a PRS trem. As for the irreversible part, you can route the piezo wires through the bridge pickup cavity into your control cavity (I know guys who've done this with both PRS trems and Les Pauls). Then it's just a matter of shoehorning the preamp into your control cavity and perhaps using a concentric pot to allow you to control the piezo and magnetic volume independently.