I had a horrible infestation in my house 2 years ago and used D-Con. It got rid of them that year, and they didn't come back last year. I did find corpses in the wall when I remodeled my family room. They were using holes cut for speaker wires as their own Habitrail (the boob that owned the house before me cut 1" holes for 14-gauge speaker wire through all the studs along the back wall). Even if one does happen to die in the wall, they're too small to smell unless it's right under your nose.
My RV had been sitting for a while and clearly had something big living under the bed in the back. It/they had chewed a 2' x 1' hole through the paneling and insulation. It did not look fresh, however. I found D-Con sprinkled around. All last winter I saw no evidence of any rodents returning (though I did spend a lot of time in there working on the engine - maybe that spooks them?).
How long does the rig have to sit before being invaded? What if I move it around the driveway once a week or so?