We use the factory fitted shower in the heads, it is fed from hot water from the engine after about 1 to 2 hours, just enough water for 4 people to take a quick refresh shower (not at the same time !!!)
The wife and I both use our shower in the head. We actually installed a shower curtain that we cut and hemmed so that it fit behind the toilet so that the storage shelf stays dry. 40gal tank usually will last all weekend. We went from a 22ft pontoon to this 3200SCR and after using a bucket for 8yrs the wife is happier than sh--. No pun intended and no#2unless emergency.