re: Sharing through-hulls and pumps
Have single manifold for all domestic salt water intakes on my new boat. However, AC and refrig units have separate keel coolers/intakes. Could link sinks/heads/washdowns/watermaker to single manifold and decrease through holds but would be nervous about AC/refrig units. Maybe others have more knowledge. Other advantage is it's easy to switch to fresh from salt for those functions when near fresh supply while being able to wash in salt and rinse in fresh anytime. Try to keep fresh to head intakes as should cut down on stink and wear.