As a Sailor, I wore my HA's most of the trips through the world, I even wore them through Southern Oceans and Squally weathers!!! so the environment is constantly damp and salty.
I did try the "ear condoms" very difficult to use if you have those battery opening to switch off/on I gave up after while. (connevans sells those)
I used the dri bag and desiccant, I swapped bag for air tight clip container to give HA's bit of more protection. And carried Ziploc bag in my pocket in case I get really wet (i still do this to this day for day races)
I had been at sea for 10 months with few weeks breaks in between in each ports (5) I only sent one HA for repairs and that wasn't due to rust. I got those HA's in 2000, My trip was in 2000 and i had those HA's up until 2008 when it gave up due to old age! (Widex Senso)