I may be missing something here. I believe the problem with flames in an enclosed space would be generation of CO...correct? If I really needed my cup of coffee, I would be tempted to crank up any of my backpacking stoves for the brief time required for that essential fluid.

Aside from that, there are lots of nutritious, tasty items - nuts and fruits, many veggies. I could easily consume cold cans of beef stew, etc., although it would be preferable to heat them.