Go to a store that sells bow hunting supplies. Get a scent based on a predator's excretions. First make sure you can stand the smell, then put just a tiny bit of it on your pack or near where it is stored. The mice will think that a fox or something is nearby and not mess with your gear.

I had mice destroying books being stored in the attic, and this settled them down PDQ when I just put a very small amount on the outside of the boxes (books were poly bagged), and a bit more on rags at each mouse hole I found. More effective than a cat, and considering my furry assassins' love of the hunt, that's saying a lot.