You can come to Canada as visitors for up to 6 months. 5 months in, you can apply to extend your visitor status. You have to prove every time that your stay is temporary and that you have the funds to support yourselves. Some type of health insurance would probably help too. Some people have succeeded in doing this a few times. I heard of somebody doing it for 3 years but if you are told no, you can leave and come back. The immigration officers can however deny you entry if they think you are staying in Canada too much on your visit visa. Visiting 6 months a year should also be ok in most cases.
The 45 months in Mississauga is an average and sometimes can change. It was 36 months not too long ago. Maybe if they feel it is getting too long, they will put more staff on it and it will get shorter again. The 24 months 2nd stage is how long it takes to process 80% of the applications. Yours could be faster.