I will guess that your destination is not Bangor. So if it is tight, file and go to CYYT (or BIKF) and then to US destination (if it has customs)
Ahhh.....no customs at destination?
In that case, if your passengers are really not wanting to stop CYYT, and you are trying KBGR, file a CANPAS arrival at overhead estimate for YYT. File flightplan to KBGR, to the eAPIS, contact US customs and give them your ETA KBGR.
File CYYT as alternate.
When you are approaching CYYT, if it looks good for KBGR, then call St Johns and ask them to inform CANPASS that you are not stopping as planned, but continuing on to Bangor.
If you need to stop CYYT, then you are already set up and they are expecting you. Then on the ground, you update the Americans either KBGR or where-ever you will clear customs, if the CYYT stop permits you to go further.
Get a sat-phone!
or a Delorme tracker and send CANPASS an e-mail in flight if you are bypassing them.
Donīt make a habit of this, do what was suggested earlier and have a good flightplanning software, and donīt make convenience more important than safety!