What *is* his role?
Having the big picture.
Tax rates, food stores, etc. are part of the big picture. Food rot isn't - it's on the order of a few percent. It shouldn't matter on the realm level. Let region lords and their stewards worry about it.
Also, I think you are still stuck in the ox cart system, mentally, where you would cart food around the realm for strategic reasons. Forget all about that.
