So I found an exploit/bug/glitch to get a bunch of food, though it takes some time
if you go hunting, you can open/close inventory to reset the animals, but keep everything you've gathered
So you can hunt everything, open/close inventory, rinse repeat and no in-game time passes
As far as the food per-day going up, that happens as you gain "slaves", which is a reward for fights
only way to deal with that is to send the slaves on a mission, which is done from the prison, but requires a sum of food based on how many slaves you are sending off