The other factor to consider during 'expedition' rides, or even fairly remote rides in the US is to include a certain percentage of food/water (and gear) as the Oh S--t buffer in case you have a significant problem in a remote area. Crossing the Mohave Desert in July I carried roughly 4-5 gallons of water (depending on the day's route) which beside the weight took up a lot of space. Although I only drank/used 3-4 gallons per day, the extra could have made the difference between life/death in some areas.