I'm glad you enjoyed the story (it's also posted on this site), I enjoyed writing it almost as much as being there.
Yes, BWCA is the American side of the border adjacent to Quetico. I saw people but they weren't behind every bush. My understanding, going in, was to go before Memorial day or after Labor day and do one or two hard portages to get away from the crowds. There were a few days on the Frost & Kawishiwi rivers where people were extremely scarce. Even elsewhere, if you ran into anyone, it was at portages. (The whole place probably gets busier as the summer wears on and everything outdoors is busier since covid). I'd definitely go again.