Honestly the reason I am "against" cruising is because they are usually floating environmental travesties
They will know exactly how much water they used down to the quart, same with diesel. They will have very tight energy budgets as well and track it by the watt hour. Their energy will likely come from renewable sources.
Instead of daily hot showers, on a small boat you get a cold salt water shower every few days with a pint of fresh water at the end to rinse.
So, in conclusion, doubtful.