Is the diameter really critical? I just measured my favorite small kit, a mimi-Trangia which I often use with a Pocket Rocket. It is about 5 1/4 inches in diameter. I also wouldn't worry about the aluminum-Alzheimer's link because 1) you are specifying infrequent use, and 2) I understand the link has been discredited.

I usually go for aluminum or titanium for leight weight,since most of my use involves backpacking or similar activites where weight is critical. Otherwise, stainless steel is fine, and really bombproof.