Also COPR is not valid for Travel, as airlines, take it as a risk, because, in case of a denied entry, they will have to bear the expense to deport. Also, say if you Travel to US ( if you have visa for US), you can still fly to the US and take a greyhound to Toronto or Niagara.
You cannot take any commercial carrier as they will not let you board it if you dont have valid visa for the travel or PR Card in possession. What you can do is to rent a car and drive across or somehow reach the border post and cross it on foot. COPR is not valid for travel but as a PR person, CBSA officers validate the status and allow the entry.