I've not camped in the area, but based on the thread title,  here is my observation.

I've personally been dropped off or picked up by a tow operator (motor boat) running from Prairie Portage to Lincoln Island on three separate occasions.  I also observed a number of other motor craft in the area during transit.  So, if you are asking if the area is motor-free, the answer would be no.  However, they are supposed to operate in U.S. waters only (from my understanding).

dd

I have not camped on them, but there are several on the shoreline from Washington Is. to US Point.  They are generally set on slightly elevated rocky ridge with small beachy cove adjacent and face east.
Around the tip of US Point to the north are at least two sites with excellent beaches, facing north, and sites are grassy, level and lower elevation than the ridge ones.