To pick a location, I understand I want to evaluate median income, a large population of those approaching retirement age, and a decently dense population.

Quote from @Jaycee Greene: If you go the conventional/DSCR route, these are considered "Commercial" loans and the properties are referred to as "Non Owner-Occupied" and, as such, the cash flow of the property is most important, and your DTI is not generally included in the underwriting.

It took about a year and a half to stabilize the property but the property is stabilized and cash flowing.

Purchase price: $480,000 Cash invested: $75,000 Purchased as a single family home with a basement and a seperate entrence.

If your partner is a contractor and wants to keep busy, that could be a different story, but I at least consider looking at long term ownership plans and flipping as very different businesses and a lot to learn on both, so not sure I'd risk losing money and time dealing with flips. 

And if there was any land available, it'd cost an arm and a leg.

And as for a multi, I'd argue it's best to build, not buy, especially if going out to the NW "burbs".

I have a 1/1 and a 2/1 and although I'm seeing lots of different types of travelers, the ones who have been booking my place have all been traveling medical professionals.

How are they coming up with a security deposit and a months rent and moving costs for a new apartment?

I am pretty averse to that type of liability due to having significant assets and a strong W2. 2.