My wife and I have some time off the last week of October and want to use it to camp in either Oregon or Washington. From looking at the sites listed on this portal, all or most of the campgrounds will close by mid-October.

Anyone out there have any suggestions? Thanks!

I cannot speak for Oregon and Washington, but I have seen that in some areas, one campground out of several in a particular district is kept open either later than the rest or sometimes all year. (This may also result in having no water supply). District Ranger stations would be able to tell you specifically which campgrounds would be available to you.
If you are interested in camping at State Parks, I know that many of the State Parks in Oregon are open all year.

Ed