I've had very good results with Bounce sheets and Irish Spring soap inside the trailer and mothballs OUTSIDE the trailer around the wheels and jack (anything touching the ground). Trailer smells great in the spring, and I think the Bounce sheets do absorb some moisture too. I have not tried the peppermint oil (yet!).
Having said that... these are just repellents. If mice have a choice of places to go, they will go where there are no repellents. If there is no other place for them, they will go into the camper, soap/sheets/mothballs/sonic noise whatever.
As to mouse traps, I have always used cheese (American or Swiss, whichever is less expensive). The key is that very quickly the cheese chunk on the trigger will dryout and harden - then the mouse has to gnaw at the bait, tripping the trap. Peanut butter can be easily licked off without tripping the trap. I prefer the traditional traps with wood base and spring steel - they are powerful and seem to kill the mice almost instantly. As someone already posted, you are actually bringing bait/food into the camper if you set them up inside the camper, so see if you can avoid that. And if you don't check them daily you might have the smell of dead mouse in your camper for awhile...
If you use glue traps, a couple things to keep in mind. 1. Keep any pets AWAY from them! That liquid/oozy glue is VERY effective. 2. If you catch a mouse/rat, you now will have a live animal to get rid of. Many people simply put the trap, mouse included, into a bucket of water where it will drown. This can be rather unpleasant if you are not ready to do that.
Farmers do use those bucket traps with water and bait/peanut butter on a can or bottle that spins - they can be very effective. I would not consider them practical inside a camper... BUT how about setting up one or two outside the camper?
Dealing with mice (and other rodents) is an ongoing job. Try all the different methods out there and/or combine them, and see what works for you.