On my first camino, the Frances, I had no problem with dehydration, but I was significantly dehydrated on both the Aragones and the VdlP, to the point where medication was needed to deal with effects of dehydration. This in spite of the fact that I was generally not thirsty. I am planning carefully this year to get adequate water on the Madrid and the Invierno. But water sources marked on maps may be dry or not functioning, as on the Aragones. So far, the only thing that I can think of to avoid dehydration is to drink a lot of water in the morning, then load up on as much as I can comfortably carry and keep my bottles filled whenever I can. I do not use packaged electrolytes, mostly because what is available at MEC, besides being expensive and heavy to carry, are tablets sweetened with artificial sweeteners, which I dislike and would probable go thirsty rather than drink. But I do drink Aquarius when available and find it refreshing.
As for food, I do what I can for breakfast, generally instant porridge and coffee heated with my electric coil, if no bars or restaurants are open, cheese, apple and sometimes bread and carrots for lunch on the trail, and pilgrim menu for dinner. Food is heavy, so I try to plan meals around available bars and tiendas, but not to run out. This may be a challenge on the Madrid and the Invierno this year. I always lose weight on camino and generally keep it off for some time. But it will be two years since I walked when I set off in October, so I can afford to miss the occasional meal and concentrate on water.