Unless there's a proper bear box, I always hang my food using my own resources. The key to keeping the mice out is two-fold. First, be sure you hang properly, with the bag well away from trunk or limbs in the tree, so that the mouse can't just leap onto the bag (mice can jump a surprisingly long way for their size.) Second, use a line that the mice can't really climb down. That generally means very thin dyneema line, because it makes it hard for them to grip (small line diameter) and it is very slick. I've done this for years now and never had the mice raid my food, even when others at the same site have.