They may well NOT stamp the passport on the way in and they never stamp it on the way out.
Keep a full paper trail of all your bills, (utility, credit, medical etc), payslips, rental, insurance, etc. Anything that shows an ongoing physical presence in Canada. Don't elect for paperless billing... Keep exact records of any cross-border travel, including itinerary, tickets etc. Be paranoid. It's a lot easier to discard stuff that you don't need than to find missing information when you do need it.