Very nicely done "intentional" result! As for the unintentional, I well know what you mean. So far I've been lucky, and the meeces have only nested in drawers. Nevertheless, I HATE finding urine-stained insulation all over a drawer full of newly rusted stuff - hate them meeces to pieces! I'll be trying mothballs in all the drawers this winter. I hear they work pretty well as a deterrent. Maybe you can find a way to place/hang a couple into your headstock. The naphthalene type should be pretty benign toward metal. I suppose the paradichlorobenzene is inert enough not to be a problem, but any mention of chlorine makes me paranoid. Good luck!
PS - if you have some camphor around (rust preventer for tool boxes), I'd bet it would work also.