Eryka, are you on a mooring ball? No dockside water?
The only difference I see is hair washing/rinsing and maybe a dab more for leg shaving (more square inches than my face - hence more water). I of course use almost no water on my hair
, and conditioner is wasted effort for me.
On our cruises I would guess my wife and daughters used water on parity with the guys, no one was counting ounces and gallons as we had ready resupply.
Personally, to me the extra consumption is worth the results.
Long hot showers can be had with a bag of sun heated raw water then rinsed with fresh, isn't that good enough?