i also had HVAC mystery issues in my first duplex when we house hacked it.Regarding the Daikin Mini Split - I have one in the 3rd story of my current home and it seems to work great for us. 

Purchase price: $145,000 Cash invested: $60,000 Finding a move-in-ready home that offers modern upgrades and country charm can be challenging—but this fully renovated 4-5 bedroom, 2-bathroom ranch is the perfect solution.

The picture makes me think of a "mini" hotel or some type of destination/STR property. 

If your unit doesn't stand out in other ways considering adding amenities like a hot tub, backyard mini golf course, making your airbnb dog friendly, etc.

Tenants in many markets already believe they pay too much (contrary to recent studies that show rent to property values have never been lower for the large US cities).If my insurance costs are not double my current rates over the next couple years, I will be pleasantly surprised.  

I've already been hearing about all the communities and mini cities that they are planning on opening around it as well.

The voucher is the most that Sec8 will pay for that person’s rent regardless of where they rent.  2) The second part of the Sec8 equation is the market rates for specific neighborhood’s and property types (SFR vs apartment, # bedrooms, # baths, utilities included vs paid by tenant, etc).

6 months later, I have doubled the size of the yard with all the clearing, performed a unit turn raising rent over $600.

Purchase price: $145,000 Cash invested: $60,000 Fully renovated 4-5 bedroom ranch on 3.3 acres.

So, I started with a couple build-to-rent homes, then a couple more, and then felt comfortable to build a mini development.