We got caught in those same winds on Lake of Two Rivers on Sunday. We were stopped on the lea side of an island taking photos when we realized that the wind had come up. We made a very hasty upwind retreat. Very difficult.
Wish we'd known you were up there! :) We headed downwind from the lodge feeling a bit too confident, as it turned out. "Only experienced canoeists should go out today," we commented, not expecting any trouble. Our main worry was that the wind might blow us too close to the two moose we were photographing. Then we had to come back upwind - yikes. There were a couple of times when a gust of wind grabbed the canoe and pushed us 45 degrees off our line. We were nervous that the wind might push us up onto an underwater log or against a stump so we didn't want to be too close to shore. On the other hand, the wind could flip us into the cold water and then we'd want to be close to shore. For a short paddle from a hotel, it was unexpectedly intense.
The Arowhon boat we were using was a nice one, but tracked worse than ours and was prone to pivoting in the wind more. We watched a sailboat get rescued, and kept an eye on some paddlers in an aluminum canoe who were struggling, in case we needed to help out.