Will you have access to shopping? What I eat really depends upon access to shopping and restaurants.
Breakfast is easy: Oatmeal and nuts/dried fruit is my AM meal, and that works for no store access. Add pastries, fresh fruit, etc. if there is shopping.
If limited access to shopping for lunch/dinner, pasta or rice mix packets and tuna packets are an, easy, cheap and good meal. Fresh green beans and other veggies last for days uncooked, so I sometimes add these. Apples last for days also.
I do use freeze-dried meals, but they are expensive and just so-so on taste, so I try to limit them.