OK. I'm slow, but....
I found the 5a accessory terminal, just top of the fuse block on the left side of the bike behind a removable panel. This is apparently switched and fused. I can easily run a wire from there to my marine cig lighter socket, mounted in the left side pocket. Then I can either a) use a cig lighter Nuvi power cord from left pocket to Nuvi on left handlebar, or b) additionally hard wire a Nuvi 12V-5V adapter wire to the back of the cig lighter socket. Advantage of a) is ease of installation. Advantage of b) is that I can have something in the cig lighter AND the Nuvi running at the same time.
Far out. Got a plan, now just need all the bits and pieces (wire, connectors, drill.....). Everything will be marine grade, so splashed water or corrosion will not be a problem. Even the cig lighter socket has a cap to keep stray metal from shorting it out.
Thanks!
Mark.