X-rated Bob wrote:
1) Are there enough vibrations in the side to drive the tuner reliably?
That depends entirely on how sensitive the piezo/preamp in the tuner are... If it works on a headstock, it will probably work on the side, but difficult to say for sure until you've tried it.
2) What do you use to keep it in place?
The thinner double-sided mirror tape. Does absorb a little bit of the vibration, but also allows for a little bit of leeway for fitting. KK, Schaller and even occasionally Fishman have used it to stick contact transducers to tops.
3) And how do you manage to have it fixed without the clip AND have access to change the battery?
If battery access is on the back, that probably means ripping it off and replacing it with new tape every time. In that case, put some fingerprints on the sticky stuff of the tape each time you apply it, which reduces the adhesion thanks to sweat, oil and dirt, and allows it to be removed a little more easily (some of the tapes can be really stubborn to remove after they've been on a month or so).
