Okay, this is easy, and there is only one answer: You want showers on board? Set up for it - it''s easy.
First, all things in the head need to be secured and set-up for water. Toilet paper is mounted inside the sink cabinet door. Sink cabinet door needs to shed water instead of allowing it in. Health needs are stored in a watertight medicine cabinet, preferably with a nice mirror. Counters and and all other things in the head need to be kept clean and clear, and towels are stored in a dry, safe place, not neccesarily in the head. Keep cleaning supplies that are safe geting wet under the sink. Make sure any drawers are safe from water. If you have an outlet, make sure it is a ground fault interupter and that there is nothing plugged into it. Plug in your electric razor or hair dryer when you need them, then stow them. The GFI outlet can handle the shower activity as long as water is not deliberately sprayed right into it.
Now, next thing is water in - water out. If you need to get a good water heater, get one. A good marine one, and don''t scrimp when you find the good one you want. You will LOVE it EVERY morning. Also, make sure your fresh water pump is up to the task. These also can be pricey, but you can learn a lot at a boat show. Finally, a good shower drain and sump pump will take care of the water out thing, and they are fairly inexpensive.
Each morning, after showering and getting shaved and dressed, take the used towel and wiped down the entire head. It only takes a minute and brings you news of any areas that need maintanence or special work to make them smoother or more waterproof. Make sure you leave the head all sparkling shiny and clean. If you need to, spray a little Febreeze or something in there. You don''t want any nose-wrinkling smells to hit you in the face when you come home. Especially if you bring a friend home for a drink and a look around your new home.
It will not take much time or money to get your boat shower perfectly suited to your needs, and you will, at the same time, adjust your ''wants'' to suit what the limitations of marine heads can provide.