Everything I've read on this forum suggests that using a rental car to cross into Canada via a land border is a viable option. I am not sure how it would be classed as a commercial vehicle since it is a simple passenger car. I don't think it falls into the same category as bus or train. Again, I still feel that the tunnel bus would be a viable option. The only way 'commercial' travel would be a hindrance, from what I understand would be using a plane or a boat to get into Canada as you must show your PR card or valid visa to board at the beginning. If the OP were to jump on the tunnel bus, he would indeed be brought to Canada, and from there they would check his information and see from the computer systems that he is indeed a PR and would allow him in either with a breach notification or without, but either way they would have to let him in. If he were to cross in a rental car, then the odds of them looking closer are that much more diminished as they are only going to look at his COPR and his passport to verify. Again, they would HAVE to let him in either with or without RO breach notification.keesio said:rental cars are considered "commercial" vehicles.
I am not sure why you think he can't get on a tunnel bus or rent a car whether it's considered "commercial" for rental/insurance purposes or not.