For some one passing through NW Wis on US Hwy 2 there is a handy little (cheap) Nat Forest Campground, Wanoka Lake, just east of Iron River about a mile off the Hwy. It is about 40 miles east of Duluth MN or 30 miles west of Ashland WI. It's a small 20 unit Forest Service Campground with water and pit toilets only. $12 per night fee with no other pass required. If you have a Federal Senior Pass it's $6 per night.
We have stayed there a couple times last year and at least three times this year. It's only about 26-7 miles from home for us so I can set up Friday morning, go home and wait for the wife and she doesn't have to use a days vacation. Pods fit in to any of the sites. Some are quite open and some are quite private for a public campground.
There are also two handy State Forest Campgrounds farther west near Brule and Amnicon Falls State Park. Similar type campgrounds but include picnic grounds. They are a little more money and require a State Park Sticker. Amnicon Falls is a nice smaller State Park with a waterfalls, covered suspension bridge and some short hiking trails.