You can access the inside of the stern from the lazzerete. Locate five inches or so above the deck, drill your plug diameter hole, feed the wire and tighten the backside of the plug from inside the laz. Make up your wires with the plug on deck, slip it back in the hole, tighten from inside and you’re done. There should be a rubber/neoprene/silicon gasket on the back of the plug flange to seal the hole. I have the switch for my dinghy davit located there. Always dry inside and is easy to access if I need/want to change it.