Depends if the property is cash flowing well.... if it is, then consider installing a mini-split system (electric).

Although as @Patrick Desjardins mentioned, with FDCPA and CFPB, you need to be very careful that you comply with laws regarding debt collection practices (reading them the "mini miranda", how often you call, what time of day you call, etc), and state licensing that may be required. 

I’ve got to put in new hvac and two hvac guys suggested I use mini splits. 

Any advice on what heating solution to go with: mini-split or furnaces?

We have placed mini splits in some of our units. 

I actually built a mini-call center to call homeowners, they don't answer and when they do, once you even mention the word "house or home", they hang up.

@Ian Lockwood , "teams of agents" is kind of like a mini realty within a brokerage.  

When you do contact them, phone or mail, you have to put in a mini miranda stating you are attempting to collect a debt to cover you from any FDCPA issues.

I am currently looking to begin my education on the development of mini storages.

I did a mini version of a BRRRR on the property right after I bought it and it was a decent deal, but I don't think a refi would get all my cash out.