I've never done more than a month long tour. Most were on the order of a week. I think the amount you carry breaks down according to the time you stay stationary in one place. If I was to ride 200miles over three days and stayed at a destination for a week i'd carry more than if I was riding 1000miles and stayed in a different place everynight.

I don't see the need to carry cooking gear if one is riding everyday and there's food along the road, personal preference but it reduces the amount of gear carried.

From what I've seen more people send home stuff after time on the road than add stuff. Whatever you determine a max load to be I'd reduce it by 30% to allow for big loads of food or water picked up for long stretches from re-supply.