Well, I made a makeshift piezo from a door alarm piezo element, more just to show that it can be done.  

I didn't make the pickup on my electric.  It is stock, the usual rectangular thing that fits under the bridge and has the piezo element near the bass foot.  I did add a DC blocking cap to reduce the "pumping" sound a bit and use a preamp I built because the one that came stock drove into distortion easier than I liked.  But that's just a simple jFET preamp with a little tweaking.

Rather than using a clipper or limiter, I tweaked the preamp to only begin to overdrive when the instrument is bowed hard.  Since it is FET, the overdrive tends more to even order distortion like a tube amp than the somewhat harsh bipolar transistor (IC op-amp) it came with (those tend to odd-order harmonics when overdriven).  That way overdrive can be controlled by the bowing.  

Probably not the sort of info you were hoping for, Ty, but maybe there's an idea or two in it that you can try.