On our two Oyster 15m ketches used in the “Tall Ships “races, we have Icom802’s, auto tuner nearby and coax out of the cabin to the port main mast midstay aerial (running backstays), starting 2m above the deck to reduce the risk of rf burns and shock. The ground is a thru hull outer bronze plate 25cm x 15 cm x1.5cm connected to the tuner ground with copper foil 7.5mm wide. The plate is 20cm above the keel/hull junction and in line vertically with the aerial and this reduces the chance of un-wetting when on Port tack. The plate is cleaned and abraided religiously at each annual refit.
I had considered putting ssb on my Nauticat 37 but doing the sums, It would be cheaper to hire a sat-phone for the brief times I would use really long range coms.
Having sailed from Kristiansand to Southend in a straight line, nonstop, I was amazed at how often I could hear and talk to Ships and Rigs in the North sea on VHF ch16.
I would commend to you the principle of allowing radio wattage to flow in the shortest straightest route by the widest possible conductors. I anticipate you could fit the Icom black box and tuner in the space above the microwave oven with the head and mic in the passage way above the 3 storage drawers, to be used from the helm position maybe.
I’d be interested in your results.