I've got 4 of the electronic things running inside the motorhome already. I went through there with more peppermint oil and cotton balls. I'm thinking if I can't get to town to get the Freshcab today, I'll put tin foil around the tires. We've also got one of those fringe things at the back of the motorhome, I placed some scented cotton balls there as well. More mothballs underneath. The inside smells great anyway, LOL! I also think I'll get more spring traps for around the tires. The traps inside with peanut butter might actually be attracting them, and I would prefer they stay out entirely.
We stored our fifth wheel in that same machine shed for years. Never had a trace of mice inside. We didn't leave loaded traps in there over winter because we weren't able to check it daily, but I used lots of fabric softener sheets inside and moth balls in the outside storage area and in the wheel wells. This thing with the motorhome is baffling because our fifth wheel had more ways for the mice to get in than the motorhome does.
I would love to have cats, but we're away from here for winter so we can't keep them. We had a weasel sharing our shop (a different building) with the cat we used to have, and I think between the two of them, they kept the place clear. The weasel enjoyed the cat food as well. ;)