One spot on that route I'd recommend which is not too well known but we've liked it each time is Kakabeka Falls Provincial Park, nice park and close to Thunderbay Bay which has a attractions and is the major center at the top of Superior so you can get anything there. The river through Thunderbay and the park was the main route down to the rest of what became Canada for the fur trade (you can walk the portage they used through the park around the falls) and the re-creation of the fort in town has been well done with the guides pretending to be inhabitants well versed in how things were.
The attraction in the park itself is the second highest waterfalls in Ontario which for us was 2 minutes walk from our site. Given number the one falls is Niagara being #2 is not too shabby a display and it's a great experience early in the morning. Where we stayed had no hookups, but there is another area in the park where they have partial hookups plus clean warm showers and a dump station. We had fun at the local pick your own Amethyst mines, the area just east of town is the place in the world for Amethyst.
Kakabeka Falls PPThere is a KOA on the north side of SS Marie. It is one of the nicest maintained and equipped I have ever stayed at. Most of the sites are closer than I like together, but it you ask they have sites around the back that give you a little room around the fire pit if you know what I mean.
