I'm a newbie to all this stuff, but wouldn't a simple packet of desiccant in a cache help with the dampness? You know, those "DO NOT EAT CONTENTS OF PACKET" packets you find in all sorts of packaging and sorts. All the caches I've run across haven't had any, and I guess micros are hard enough to simply store the log, but bigger ones could hold a small packet or even desiccants that are small tubes to help bring the moisture down.