If you are found actively fishing or camping on the Canada side of the border you might get a ticket.  I have not heard of anyone being ticketed for being near and just looking at Warrior Hill or the Pictos on LaCroix.  Theoretically the border "route" is open to travelers of both parks to make the logistics of travel and some portages manageable. 
There are several very nice BWCAW campsites near and somewhat southeast of Warrior Hill (on islands) your permit will cover.