Looking on timeanddate, from the southern tip of Center Island of the Toronto Islands, the Eclipse looks to be about 99.98 % obscuration. 99.98 % might just be good enough.
Lots of beach area to view from and avoid crowds plus I'm thinking being out in the open there on the island, the breeze may keep the clouds moving.
The southern tip of Center Island around where that Pier is is coordinates 43.61 N, 79.38 W. Just on edge of shadow track, may be slight margin of error.
Are not the Toronto Islands generally a bit Sunnier than on the mainland ?
If not I am leaning towards going to Montreal, may be drier to the north.