I agree and know the feeling. This is something I've been thinking about since the first time I played this game. I really miss this dimension of the game.
The model I'm planning to incorporate into
patSH3r is not focused on proviant in that specific sense, but more in a abstract one. The crew gets affected by war discontent and exhaustion the more time they spend at sea. This will lower their morale and ability to recover. By a month in a Type II the crew will be pretty exhausted.
I'm not not completly certain how the model should look like, so I'm open for suggestions.
I've got to solve the crew rotation first. I don't want to be left at sea with a fatigue model that requires me to throw the crew around every minute.