The first pass is based on the "Gross Yield" which is simply the ratio of annual estimated rents by bedroom count divided by the sales price. 

We spent $40,000 to restructure our house (basically combine two bedrooms to an airbnb unit).

I've been hearing mixed thoughts....but my research shows a lot of development in the area...and the land value of the particular property I'm looking at has more than doubled since 2016.

Yes, it will double in 12 years, but that’s a very long time.

My houses are multiple bedrooms so most have kids. 

All 3 properties are in the southeast and are 3 and 4 bedroom homes in good areas.Do you use two year leases?

In my area I see a lot of "Mother In-Law" apartments and other non-legal 1 bedroom tack ons... often these are garage conversions. 

Sounds like constructive fraud, but you probably need a legal pro to help you.If it were me, I would double check the lease and the application and look for a clause that says something like "applicant / tenant affirms that the information provided is accurate and true". 

all in al great investment opportunities.I have a 3 bedroom coming up for $360K- new paint, carpet and kitchen, as well as a potential flip for aroudn that price as well.

Properties in my area have nearly doubled in value over the last four years, comps that old would be worthless.