I keep some AAA's (alkaline) in a toothbrush holder (holds 8 of them), with a small piece of cardboard between the rows to avoid contact. Since it has a small hole in the end, i'm hoping no vapors collect. In selecting all my devices (lights, radios, steripen, etc), I have been successful having almost everything use AAA batteries (radio uses AA). One of my main considerations is minimizing types and sizes of batteries I need to carry, though I'll guess you don't want to consider other equipment that ues smaller batteries.. I think "C" and "D" would be a tough one. I'd look for some kind of soft case, maybe a small calculator case, camera case or stuff sack.

Michael