Outland sponsorship approval does not take 6 months, it takes 35 days
Outland sponsorship does NOT take just 35 days - that's just the first stage of the process where the sponsor is approved. After that the application goes to the overseas visa office where the applicant is assessed, and that process takes 4-9 months. So you're looking at a total of 5-10 months for her to be approved for permanent status. Before she has permanent status she has to get a visitor visa to enter Canada - if she is from a
non-visa-exempt country. That requirement will not change just because she marries a Canadian citizen - in fact, it will be harder for her to get a temporary visa once she's married to a Canadian because she still be not be able to prove that she will actually leave Canada at the end of her authorized stay. Most visitor visas for spouses are refused - for all the same reasons she has previously been refused. They know she has a romantic relationship with a Canadian and, therefore, they will never believe she intends to leave him behind and go back home again.
It's too bad about his father being ill and wanting to see his son married in the church - but CIC won't care. They need not to waste any more time trying to get her a visitor visa so they can marry in Canada - they need to just get married in the States and get that PR application on file in the hopes that it will be approved quickly and then she can come to Canada and have their church wedding. The hope of marrying in Canada now is a lost cause.