Generally you can weed out many individuals based on income, credit, employment history, previous residences, and overall behavior compared to other candidates. 

It's so simple, anyone can pull it off, and many of my clients are first time investors employing the exact same strategy.I think you already have it pretty much figured out, but I might suggest incorporating some kind of creative housing in the mix to increase revenue, like STR/MTR or renting by the bedroom.

On a positive there are 15-20-30 year amortizations and increasing income qualifications including instant approval and AVM (no appraisal requirements) for very clean applicants, and creative documentation for self-employed borrowers or investors such as bank statements or even DSCR (usually up to 75%LTV) for investment properties. 

Are there various strategies/corporate structures that can be employed to minimize the tax obligation to Canada when investing in the states?

.- Very low appreciation unless there is a large market shift -- major new employer, city takes many housing units offline via eminent domain, a college greatly expands without additional housing, etc.The list goes on.

There are ~160M employed persons in the US. 

I would definetly consult with an attorney before and ask if you would be able to get these people out of your property in you needed.If may just be easier to steer clear and try to find a good applicant with a SSN#Or, if there is a company that employs a lot of people without a SSN# you could reach out to the company, ask if they need housing for there employees, and then rent to the company instead of the person.

A jobless rate of 3% or below is widely considered "full employment" by economists, or the point at which most people who want a job have one

If I form a LLC, I do not want to be subject to self-employment tax.  

Haven't done LTR though, I like that the tenants are new, fresh and employed so far and haven't had much incidents.