I'm a liveaboard on a sailboat and I store all my tools and do all my reloading in the aft cabin, which is about the size of a small closet; humidity is definitely a problem and everything is kept in airtight containers or heavy zip lock bags. As a rule after I use a tool/die I wipe it down with a G96 soaked rag before I seal it back up. Humidity collecting on cold components while in use can happen if I have a heater on while I'm in there, but as long as I'm careful and keep some airflow everything is fine. My biggest challenge is weighing powder on days with more than 10 knots of wind, or days with frequent harbor ferry traffic. As most can imagine, electronic scales are useless on a boat, as are the nice electronic powder dispensers I would love to use, so if I want a weighed charge, I have to use a beam scale.