Campgrounds in Door County and in NF near Ely, MN.

Bear Head Lake State Park near Ely has been awarded as one of the best in the nation. But - the loops can be narrow with trees and tall brush, making backing a bigger rig challenging. I struggled with my 5th wheel. Best to call them for advice first, and then see what you can reserve.
Fall Lake Campground (NF) is another great spot. A little better for bigger rigs, but again you should spend a bit of time researching then reserving - some say no issue and love it, some say too tight and confining.