I'd probably advise you go with 2 x panniers and a handlebar bag. You should be able to fit everything you need to be comfortable in there using readily available gear and some common sense.......no cast iron cooking pots.
That's exactly what I'm doing for my next bike trip later this month. The amount of gear I'm taking for a two-week winter trip will be the same or a little less than I used for the last one-week summer trips.
The only time I used front and rear panniers was when I was on a route which had me away from supply points for multiple days. Carrying enough food for four days added some bulk to the load.