Shouldn't be that complicated. Food, IMHO, is a minimal concern. Water is much more important.
I carry a lot of water but I also carry a Sawyer filter. But with that, I will not drink water downstream from civilization unless I have to and then, I chemically treat it too. Although the filter will filter out bacteria, it will not take out viruses.
For instance. I ride Banff Ab. to Elkford B.C. Single track trail, a lot of gravel roads and perhaps 10 paved miles. 110 miles total distance. Bolton store is close to half way through which is good to top off water and get some food. It takes me 10 hours to do that on a mountain bike loaded with gear. That is tent, clothing, sleeping bag, etc... I normally have a pair of bottle holders ty-wrapped to the front fork with a couple 1L collapsible bags in my backpack or in my frame bag. If I need water on the way, I have a Sawyer filter and there are many ice melt streams on the route.
The next day gets tricky as Sparwood is 20 miles out of Elkford before heading up Flathead Pass, Cabin Pass and Galton Pass where there are no services anywhere. Water becomes the
#1 concern then over food.