I wouldn't worry too much about losing weight. Some people do, some people don't. If you eat enough, you won't lose weight. At your weight and height, you need to consume around 1800 calories/day as a base. Then, to counterbalance the walking, if you burn 250-400 calories per hour and walk 5-6 hours per day, that is another 1500-2400 calories. Total need: 3000-4200 calories depending on the day. It's actually not that hard to consume 3000 calories per day, especially if you include a couple cafe con leches, a couple glasses of fresh squeezed OJ or sports drinks, and then some beer or wine to end the day - that adds up to about 500 calories without even eating anything - just beverages. Add breakfast, 2nd breakfast, lunch, and dinner and you can probably consume the remaining 2500 calories without even trying. On days when you need more calories due to longer and/or more strenuous walking, you can definitely make up the difference with snacks.
For snacks - salami, cheese, nuts, fruit (dried or fresh) are all good with plenty of nutrition in them.
