There will be some giant surprises to many there when you have to start paying engineers for frequent evaluations and making the structural repairs required.   

Notably, short-term rentals are categorized as non-residential properties.

As others have commented - DSCR Loans tend to be a great solution for people in your exact scenario - fed up and tired of giant hassle and paperwork for conventional or bank financing - not worth the often pretty small benefit in rate or terms.Check out this article I published last year on BiggerPockets on what to expect documentation wise for DSCR Loans - they have become a nice blend between solid underwriting and doc sets needed, but not too much (and not too little like notorious "no doc" loans)https://www.biggerpockets.com/blog/what-documents-do-you-nee...

Heck I’m staring at a giant multi-level waterfall with an artificial lake full of ducks and geese as I write this. 

Part of it is financial returns on his $ (though that's not giant). 

What is typically expected considering approvals/permits take notably longer to get in the Northeast.

We're obviously not able to 1031 so my wife and I not only tie up our savings in the project but take the hit on capital gains. 

I have been a landlord and investor for over a decade AND also work as a senior/regional property manager so I feel like I see both sides and have some good insight on this- manage yourself if you have the time and fortitude to do so, you will make mistakes but it will pay off, get a real estate license (not hard to do plus you can sell and buy properties and get commission) and know the laws, be willing to do the research, NO ONE IS GOING CARE AS MUCH ABOUT YOUR PROPERTY AS YOU- that being said, not everyone wants to has the time ect or headache or likes asking for rent…FIND A MANAGER THAT ALSO IS A LANDLORD INVESTOR, I can’t tell you how many property managers I’ve tried training and that failed at our company because they just don’t get it from an owner or investor side, like “no tenant we aren’t going to come replace your stove again, no we aren’t going to clean your bathroom cause you didn’t , ability to analyze when to do maintenance and not, ability to explain to tenant owners POV, I tell every owner I am not telling you anything I haven’t done or I’d do my self, a lot of property managers are blue colar type workers and have never invested in their life and just done get it, 4 out of 5 property managers fail at my company because of this especially for single family homes, find a PM with speciality in SFH for your area, for example, a PM in Birmingham MI (upscale area) will fail in Detroit or lower end markets (but that’s were the best ROIs are)

It's just I came into this with a background as a classroom teacher and high-stakes language exam coach and I really didn't understand the immense help that my experience managing the student-teacher relationship has given me in learning how to manage the landlord-tenant relationship.I also had no clue how much of a leg up that same experience had taught me to deal on a personal basis with public officials such as magistrates, code enforcement officials, court clerks, and of course law enforcement officials, here in PA most notably our state constables.The last thing that really helped has nothing to do with me.

If they are not able/willing, then give them the option of breaking the lease without penalty.