Visitor from the Netherlands coming to see Canadian boyfriend

I am trying to get my girlfriend over here (to Canada, I am a natural born citizen) so that we will be able to live together for a year legally and apply as common law partners for her to get her PR.
The plan is for her to come here for her allotted 6 month time period (she doesn't need a visa as her country is exempt) and I will support her. As the 6 months came to a close she would apply for extension with something from me showing that I am willing and able to support her while she is here. If she got a 6 month extension, then we could apply as common law partners after that.
I was reading about how she might get refused if she says that she is coming to visit me (and she wont have a job when she comes, but her family is in Holland).

I am really wondering how to go about this. Would it be better to tell the border guard up front what her intentions are or would it be better to just say that she is coming to travel or something along those lines? She will have a return ticket booked when she enters the country.

Thanks in advance for your help