Also clean up anything that may provide bedding. Of course you can't remove the insulation but I had a pile of moving blankets and rags in the garage and they turned it into a condo. It was a huge nasty mess.

Usually I only struggle with mice in the winter (my house is backed to a wetlands preservation) but we have been fighting them all summer. I don't like to use poison either but it is supposed to dry them out so they won't stink. Home Depot sells some stuff (it's green) that works good as bait. I always used PB but it seemed to stop working after awhile.

Also pet food was mentioned but we put anything in a container they can chew through into rubber maid bins in the pantry. That helped a lot.