As I understand it, inventory has 12 slots, 6 of which are for ready or equipped items.

How do you handle things like rations?  A single travel ration is good for 2 days.  Do these stack to any degree?  Or does six rations take up six slots?

Hey Greymark, currently six rations counts as six slots. They can carry more (up to double their weight allowance) but are encumbered and act at disadvantage.

A days worth of food adds up in weight in my opinion but there are ways to mitigate this (i.e. transport, henchmen, supply caches etc) for longer journeys. 

I imagine allowing for some Wilderness Survival rolls to forage and hunt can also help conserve supplies.