In our earlier camping years, we used a Palomino pop up that my BIL filled with moth balls one winter to keep out the mice. I detest that smell. We did some research and with some ventilation and a huge brick of Irish Spring soap, we got rid of the smell. After inspecting the camper and finding no avenues for mice to gain access in the first place, we continued to use the soap until we moved up to the hybrid. Every time I smell Irish Spring soap it makes me think of camping which is a good thing.
We haven't used the soap in the new camper yet, as it still smells new and I like it that way. I used to cut the bars in half and throw them in the various compartments. You might try to set them in a small tray like some of the microwaveable meals come in as they tend to get soapy residue on the floor as they bounce around while traveling.
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.