Sometimes the initial recalculation is a bit premature or incorrect, and after following up the client will get a second, more accurate/permanent figure.

Finance construction, convert to permanent financing with a traditional 20% down using the equity gained during construction.  

Some keep the RV section separate from the permanent units. 

Sorry I don't have any exact answers for you but somethings to think about.What is going to be a permanent change to your property and who is going to own what if/when the tenancy ends.

The beginners needs to learn property management themselves to keep expenses down and stands a better chance of surviving without a permanent pm on the payroll.  

I am Korean-American, and while I lived and worked there for 5 years (3 years Active Duty Military and 2 as a Civilian), I grew to love the country met my wife there and now thinking of living there permanently and retiring there as I build my REI business here in CA as well. 

If I decide to keep the place the lender will allow me to sit at this current payment for several months before placing permanent financing.

The numbers have been demonstrated ad infinitum; two of the factors that make real estate, especially buy & hold rentals, attractive vs. other forms of investment are leverage and permanency (the house stands 'forever', at least from the perspective of the investor's lifespan).

One of the cons with any FHA mortgage is the permanent PMI on the loan.

If you really feel you need AC though, you would probably be better off getting a couple of nice window units and having them permanently installed professionally, which you can do for a fraction of the price of putting central AC in.