I strongly suspect you have a better idea on this that almost all of the people on here. Since you can find water on the hike you want food with a minimum of water. There's a good reason the standard, albeit expensive, answer is dehydrated food. Otherwise, look for foods that naturally have little water in them.
(While I consider 6 miles a pretty short hike I haven't done an overnight in 30 years and normally there isn't enough water around here to to make carrying a filter worth it so I don't worry about low-water foods. I actually do have a very small filter in my emergency gear, but it's never been used.)