If you read the forum, some people claim that's what they do. You would just have to be careful that the card is not lost when sent to you overseas.
Canada does not have passport check leaving the country. The airlines check the passport as a matter of identity confirmation, and the PR card is not required. It's coming back that's the problem.
If you really need to travel back to Canada while the PR card is not available yet, you can apply for a permit at the local Visa Office. It's not that you cannot leave, just that it is a lot more problematic without the PR card.