You can run metal conduit, or square tubing. It is great against mice. You could also run split nylon loom. I had an old trailer with chronic wiring problems, which continued until the day I pulled new wire in a nylon (corrugated) split wire loom. Flawless after that.
With all of the soy based insulation out there, mice are likely to be an issue unless the wires are out in the open or enclosed in metal.
The original wiring ran down a one or two inch square tubing that was structural to the trailer. As I replaced the wiring, I found a sharp shard of weld metal about two inches inside the metal tube that had been intermittently grounding out the old wiring. That was a bit of a pain to file off... For some reason, mice were never an issue. I guess 1/8" steel will do that.
FWI: I use marine, pre-tinned, wire for all of my rewiring, as it has great conductivity and doesn't corrode much compared to straight copper wire. I also use crimp connectors with heat melt adhesive inside to seal out water. I get most of it from Del-City.net
All the best,
Peter