When you walk a lot like you do, nutrition and hydration are very important. Rice and eggs are two things that provide a lot of energy, and are not heavy on the stomach when walking.
Canned preserves are also a very good option, although I think it is not for those long walks, the weight can be excessive.
I think that mate could be the best option, it provides a lot of energy and satiates the stomach, but as you say, they have those contradictions.
Crackers or rice toast is a very good option, the little ones are very light and very satisfying to eat.
It's incredible how one gains eating experience as time goes by.
Thank you very much for sharing these experiences dear friend @lauramica
have a great day