Had a sump on the last 3 liveaboards we had... both showered nearly daily. As the last shot before shutting down the shower, one of us would pour about 1/2 cup of Simple Green down the shower drain every 2-3 days. Kept things smelling clean and sweet. Sump located in the engine
room on the last 2 boats with easy access to clean out hair, etc from the strainer about once every 2 months. Not a big job and the Simple Green made it a fairly easy and not unpleasant job. I would opt for a similar setup on any future liveaboard
we might have.
I've delivered a few vessels with bilge draining showers and would counsel against going in that direction for reasons of odors, particularly ina tropical or semi-tropical climate, and unless maintained regularly, a good chance of clogging the bilge pump