I am thinking P bass pickup cover vibe in wood over the end of the fingerboard with fixings to the side of the fingerboard. I could prob run a trailing wire around the back to the bass past the cutaway because I NEVER use that end of the fingerboard so that is not an issue.
The fingerboard extension is https://goo.gl/images/WWvE4E
BRX, the present pickup is piezo under the bridge.
All this needs to be tempered with the knowledge that I am musing about this while camping in France so it might just turn out to be a pipe dream , However, it does seem possible.....