A couple Tuna packets, no water no mess open it up and eat it. You could all do what CM said and throw a couple hard boils in there as well. Could also just drain the water out of the tuna can in the morning.
Other then that there really arent many easy choices for protein other then the drinks. Consider cooking up a bunch of of chicken breast and playing with that. Mix it with brown rice, throw it on a salad, make a buffalo chicken wrap.