I figured out how to add USGS Topographic maps to the BWCA/Quetico interactive map. To see them, just change the map type in the upper right corner of the map. Sometimes the tiles take awhile to load. Also, since they are US maps, the Quetico isn't completely covered.
OpenStreetMap project and it and its contributors retain the copyright on the tiles. I am looking at making my own tiles using the USGS maps, but in the meantime, this works.