Sorry I don't know the rules for flying from Canada, but can you do curbside checking at the airport? Use a backpack for a carryon bag, that way you have one hand for stroller and a hand for child (if they don't want to be in stroller).
The other choice would be buying a stroller and have it sent to the resort. I knew a person that every year for their son, they bought a stroller, used it for a week, and then gave it away. They didn't want or need one at home and they figured you spend $50 for a stroller, it's cheaper than renting from disney for a week.
Of course you could rent from an outside company. Pretty sure that's cheaper than disney.
I've never traveled with a child alone. I'm just trying to give some ideas. I'm sure others who had traveled with kids as the only adult will come up with better suggestions.