Just did similar on my ‘95 Islander a few weeks ago.
As mentioned above, I ran a 10‘ USB-C cord out the side of the hard top electronics box, and through the u-channel that the spreader, E-box power, and NMEA wires run under. At that point, I could get into the starboard aluminum tube through which some other wires exit that run up the aft vertical tube, but didnt think I could subsequently make the corner into the horizontal tube supporting the aft side of the hard top (had previously tried to route some other wires around that bend with no luck). Ended up just running the gopro power straight aft through the spreader light bracket and then zip tied it externally across the back side of the aluminum bar for the hard top rocket launcher. Then down to the gopro, which is mounted to a ram mount amidships on the underside of the aft edge of the hard top.
The small zip ties aren't the most elegant solution, but until i figure something else out, they get the job done without looking too unsightly.
Picture(s) would be way better than trying to describe it, unfortunately. Have to run over and replace a thermostat on one of my 150’s tomorrow or Tues, so will try to remember to take a few pics of how I routed things and update the post.
