We tried dryer sheets, peppermint oil, mothballs, electronic repellants and nothing was successful in keeping the critters out. I finally built a barrier using aluminum flashing similar to what "More To See" described above, except instead of surrounding the tires and jacks, I surround the entire MOHO. I have a removable gate to get the RV in/out and have been rodent free for about 7 years now.
Also, as noted above keeping the mice out of the inside of the rig is only half the job. Before the barrier I had to remove and repair my generator twice on my previous rig due to mouse damage.
Lou
05 Travel Supreme Envoy