Lack of liability insurance also spelled the death of LOL (Lap of Lake Ontario) 1,000k/1,200k, as well as a few other routes we used to run cross border in Central/Western, NY.
As Dave mentioned, we've been working on this for several years to find insurance, or link up with a Canadian club, but have found no acceptable solution.
Now, if somebody wants to ride LOL, I'm happy to forward a cue sheet, but it won't be as a sanctioned event. I think it would be pleasant as a low pressure week's tour. If you've never crossed borders on a bike, it's an interesting thing to cue up in line with the cars, semi's, etc., passport ready, and every crossing I've used treats bicycles differently.
Pete