The only time I would consider front panniers would be to hold heavy winter clothing that is bulky but light. The more surface area you expose the more interference with steering of the bike when there is any amount of cross wind. There is an old adage among backpackers that the larger the backpack the more stuff you will take and the more weight you will carry. Same applies to panniers.

For food I take rice and pasta and spices and then make stops at markets to get tinned meat and veggies for the following 2-3 days. Easy and fast to boil water for the rice or pasta and add whatver to it. This setup takes up very little space in my panniers. My clothes and tools are in one of the panniers and my sleeping bag and a ground cloth are strapped to the top of the rack.

With a very long distance it helps to switch the front and rear tires after 1000 miles as most of the wear will be on the rear tire.