So all the big companies are strictly offering new interior and exterior unit replacements for anything over 4-5 years old. 

Also, they are very strict on the short term rental business (not that it completely cuts it out of the game, but they don't make it easy)If you were here, with your real estate license, and thinking this could be the next big area people start seeking out what would your move be? 

Did residential for 20 years and done with toilets, tenants and trash... but hard to answer your question without more context of your overall portfolio, investment objectives etc...strictly for beating inflation residential is probably the better bet as rents will adjust more quickly.

I'm starting my first rental in a few months on a lake that has a strict HOA in Monroe County, PA.

In my opinion if you are strictly going for the investment strategy and plan to begin your real estate investing journey I would try to be patient with finding the right property, preferably a duplex or larger.

But the payment would strictly be going toward interest and I’m left with the entire principle when the 5-7 years is up.

So, lending guidelines have become more strict to avoid occupancy fraud, especially with multi-family properties.

Very strict no refunds due if the guest cancels unless they  have purchased an insurance or protection plan 

Unfortunately, out here in MA there are some pretty strict lead laws.

After the year is up, I plan to make it strictly a rental property.