I have tried the following by themselves and together with no luck at all.
Bounce dryer sheets - covered every inch of the floor, drawers, cupboards, and under the bottoms of drawers.
100% peppermint oil from a farmer who grows and distills it - the stuff is so strong dipping a toothpick and shaking it off will take your breath away when you put in your mouth. Placed in small bowls with cotton balls as a wick. The funny thing is you will not find mice in a peppermint field but it doesn't bother shrews.
Pure Fox Urine sprayed on the blocks, stabilizers tongue jack and tires.
Mothballs, cedar moth balls - hanging from the underside in nylon stockings and scattered around on paper plates in the camper.
d-Con and other brands of mouse poison, mouse traps and sticky traps.
Filled every crevice and hole with expandable foam.
Stainless Steel scouring pads stuffed in the corners of the slide outs.
The slide outs have a in-frame slide mechanism with 3" holes through the frame. The Stop Cups don't completely cover the holes so mice can get into the enclosed underbelly. During the summer when the slides are out all season the 3" hole is totally exposed except where the 1-3/4" diameter tube goes through. I have another thread addressing this problem. See Actuator through frame holes
. 95 views and nobody has an idea on what to do.
We don't have power during the winter to use ultrasonic devices. The only thing I haven't tried is eucalyptus oil. The little buggers still get in.