Is this a feasible security measure for my retail iPod Touches?
You'd be better off looking for a sticker to put on top of your security sticker, and stick the sticker sandwich on the back of the device. Just use something that would be too time consuming to remove before trying to exit with the device, which would set off your alarm.  The theory being that by not hiding your effort to thwart a theft, you may deter the theft to begin with. Otherwise, it looks like a free iPod touch that nobody will notice is gone. I'd make it as obvious as possible that there's a thief detector installed on the device.

Also: read about Find My iPod Touch