This is tricky. I'd say that if you think you can make it to BGR direct, then go ahead and if you need to divert, then divert. It may take some time to process you on the ground and CANPASS may give you hassle, but that's life.
If you think it's going to be quite tight to get to BGR and there is a high probability of diversion, then I'm going to give you a rather biased and possibly unhelpful answer: Make sure your flight plans are accurate and that you can trust them. If you or your provider sets up whatever software you use correctly, very high accuracy can consistently be achieved. Not to toot my own bugle but, as one example, the system that I use regularly produces plans for CJ / CJ1s that are within 5kts, 3min and 50lbs.
Sending your actual figures back to the guy who makes your flight plans is a good start. Over a few sectors (hopefully with different flight levels / power settings) some trends can emerge, and with this info the aforementioned guy - perhaps together with the flight planning software people - can tweak various settings in the system to make things more accurate. You can and should test the new settings on a "comfortable" sector to see how accurate they are (and adjust further as required). Then you have a product that you can really trust and rely on.
You could also specify extra reserves for the calculation, e.g. go from 30 to 45 or 45 to 60mins holding fuel.
Once this is done, you could ask for sample plans with various permutations of power settings and flight levels, so that you can get a handle on how much fuel you'll actually use to get to BGR directly. It's a good idea to do this at STD-48 or later so that the latest forecast winds are available for the flight planning system to compute with.
But if you really want YYT up your sleeve, then I think the only way to do it and stay compliant with the rules, without SATCOM, is to have a bloke on the ground (perhaps your trip support company, if you use one) watching you on FlightAware or your tracking website of choice. Once you (hopefully) zoom overhead YYT he would cancel CANPASS there.
Hope this helps!