I landed in December and was planning on taking a vacation back to the US at the end of this month. I still have not received my PR card and so thought I needed to reschedule. However, I've read that a PR card is only needed for returning to Canada via commercial carriers (planes and busses). If this is the case, could I drive back to Canada with my COPR, Passport (stamped with my landing date & visitor's visa still active until OCT 2016), and something like a letter from my current employer expecting me back on x date? Thank you!