Be careful not to let the rat know he's getting to you. When I was in high school we had a pack rat that similarly eluded all attempts to trap him for several weeks. We left for a weeklong vacation and upon return realized the rat had gotten into the fan in the shop freezer, which was full of meat. It was summer and a total loss of all freezer contents. To this day my dad thinks the rat committed suicide as a final act of spite.
I got one I didn't even know I had when he wormed his way into the outside AC unit. We heard the fan puree him from upstairs. Made an awful mess.