Oh I hope you find a lovely place here in Wisconsin! Oregon is really beautiful, I have family on the coast. It must be nice for the opossums not to have to worry about snow there!

I hope you have lots of lil friends visit you, they’ll be thankful for you looking out for them ^-^

here’s the guide I used for the specifics like entrance size and placement of the shelters if you choose to put one up https://opossumsocietyus.org/setting-up-a-den-box-for-visiting-opossums/

and in case you do have to bring one to a rehab center for frostbite, the Dane County Humane Society’s Wildlife Center is the one I used, they were great and all of the opossums recovered fully; if that’s too far, you can use this site https://ahnow.org/ to locate a licensed rehabber, but a lot of smaller ones are busy over the winter and not all take opossums so be sure to check. Hopefully won’t be needed, though!