To end the speculation, I've now tried the pickup and found I didn't need to use any tape at all, so there! ;-)

The cable from the pickup when fitted was easier to route over the top of the guitar, and doesn't get in the way of my fingers or the pick. I thought it might do and that I would need to tape it in place to prevent it fouling the strings etc., but that turned out not to be necessary.

The pickup sounds OK to me through my small amp, but I'd like to hear it through a proper PA before I commit to the more permanent solution of fixing a kack socket into the guitar body.

Thanks for all the helpful advice.