>>96804061
>50ish NPCs all eating supplies on the ship on top of the party
Kek, you wish. For the first couple of chapters of campaign (probably till lvl6) they wont be able to get a ship that can run a crew bigger than 8. I think 20-25 crew will be tops I plan for them for a "bigger" ship options later in the game just so they don't end up micromanaging the characters on the ship into forever.
>A5E has a (simple) system for item durability too.
I think 3.5e hardness system works flawlessly, especially if your throw monsters at them with powerful sunder attacks.

>I got a handful of sea critters for them to maybe run into. Young sea serpents, ocean Chimera (shark, narwhal, lobster), and worse things if they decide to travel through more open ocean.
That's all planned. Subnautica gave me tons of inspirations for semi-submerged cave systems that would work as dungeons so swim checks, fort saves for holding breath, navigation and spatial awareness will be key. Also one PC wants to play a ranger so some kind of amphibian sharkdog would be very useful. Water really does give tons of options for encounters, including the Z axis movement, especially with creatures that can dive and swim at the same time.