Bridging Open Work Permit

My current CRS score is 479 and the last few CEC draws have been between 500-510. I have seen a couple of videos in which they mention that if I feel that my CRS score is near to the cut off score for PR applications then I can include a letter in Bridging Open Work Permit and request for some time to stay in Canada. My work permit is expiring in a month and I would like to know if some one has tried this or knows something about this procedure? Basically it will be applying for Bridging Open Work Permit but without an AOR and a letter mentioning as to why I need more time to stay