If you have scorable US credit, you'll get better terms.

It can be a positive for short term rentals (if in a good area) to be near the airport.

I would try not to tie up any of the principal in down payments.Personally, I had a family member do this same thing, but they used an investment portfolio as the collateral instead of real estate.If you play your cards right, this might be the only short-term money you ever need.Please let us know what you end up doing.

Whether you’re targeting strong cash flow or long-term appreciation, understanding the dynamics of each neighborhood is key.

Quote from @Byron Umana: If you're just getting started with short-term rentals, there's a lot to learn—pricing strategies, guest communication, automation, and more.

Then do a thorough research on tenant applicants (note: leaving this to a PM may be hazardous to your financial health) and choose the one that is most “stable” with the best potential for long term tenancy.This advice is contrary to maximization of rental income, but IMO will reduce expenses of tenant turnover, property damage, property management fees so much that the difference in bottom line income will be quite small.  

We do long-term rentals and practice BRRRR on every deal.

Not much in terms of online reviews as far as I can tell

However, I probably would not upgrade it but I would rent it out LONG TERM at least until you know your long term status in Portland.  

If you are doing rentals, especially long term rentals, you are unlikely to be able to live off of those for a while if they have mortgages.