I use the "Luggable Loo" also. Even though you let people know to "go" before
you leave the dock, 3 or more hours out and with water to hydrate, it can sometimes be difficult to hold out that long. No privacy with our 21' bowrider either, so I got one of these privacy shelters that does the job just fine; also good for changing in or out of swim trunks or suit.
https://www.amazon.com/dp/B00MDV13YQ...E6XVO9W87&th=1