MICE - these rodents can destroy a camper. They love to make nests out of the canvas and bedding, which means they chew it up. I've seen pictures of the damage mice can do to the canvas and bedding in a pop up, and it isn't pretty.
Over the years there have been all sorts of mouse deterrants talked about to keep them out. From Moth Balls, Irish Spring soap, Bounce Dryer sheets, peppermint oil and many more, but most are a myth and don't work. Let me give my thoughts on these-
Moth Balls- I used to swear by these since I always kept some near where the pop up was stored or parked. Never had a mouse problem until after our move last year when they were over-running the garage. I put out 4 boxes and still had mice around. Fortunately none ever got in the pop up. One thought on moth balls, the ones we bought were from the dollar store and did not have much odor to them. Also the mice weren't deterred by them as in the past. If you use moth balls, buy strong scented ones and place them near the pop-up, not in it. If you store your pop-up outside try a plastic shoebox with a few holes in the lid and the box of moth balls inside, placed near or under.
Irish Spring soap - I've read stories about placing a few bars in the pop up before winter storage to deter mice. But then I've seen pictures and read stories of mice eating the soap. Yes, it's true that mice do eat Irish Spring soap, and it has no effect as far as deterring them. Check out this guy's video of his mice and soap test- https://www.youtube.com/watch?v=IhQjxTwQdpk
Bounce Dryer sheets - Another story I've read is where mice have made nests out of these. If you think about it, how long does the smell really last when left out in the air? My guess is a few weeks at most, then nothing.
Peppermint Oil & more - Some say peppermint oil on cotton balls and placed in the pop up will help. I've also seen other oils and herbals used to deter mice. I have the same thought here, how long will the odor last?
I have seen people recommend a product called Fresh Cab that deters mice. The odor is said to last 90 days. It's a blend of different herbs and extracts. Since we haven't used this product this is only info passed on.
As I mentioned we had a LOT of mice in our new garage, coming from the neighbors shed. One night there was one waiting at the door as I came out, like a dog waiting to come in the house! I was seeing them all times of the day and night in the garage, so it was war. I tried the old fashioned traps loaded with peanut butter, no luck. I put out sticky traps, no luck. I put in two of those electronic pest repellers, still had mice. Rigged up a red-neck mouse trap, yea that was a waste of time. My answer finally came down to D-Con. Kill the little buggers before they did get in the pop up. It took several cakes of the stuff to finally get them under control. I keep some D-Con out now all the time, and haven't seen a mouse for a couple months, Thank Goodness!
Update 2018: Since I've used the D-Con there has been no sign of any mice all winter. Still have a few blocks sitting out, check them every week or so for activity. Two blocks did disappear when the first cold snap hit back in November, replaced them and haven't seen any more signs. Thank Goodness!
Update 2019: The D-Con remains untouched. No evidence of mice in garage.
So besides relying on the D-Con or other methods to keep mice away, the best way is to keep the interior of your pop up clean. Just one fingerprint from someone who has food on their hand is enough odor to attrack bugs and mice. We always clean the inside after every trip with a disinfectant wipe, from the table and counter tops to door handles and knobs. And I'm guessing that's why with all the mice we had in the garage, none went in the camper.