I increased the maintenance and Capex for a combined 20% ($5,832 anually), vacancy 8%.  

A blended rate is a combination of interest rates on various loans that gives the total amount of interest on loans aggregated in one.For Example:Loan 1: 10,000.00 @ 4.00% InterestLoan 2: 5,000.00 @  9.00% Interest You're blended rate would be 15,000 in debt @ 5.667%

This, combined with putting 20% down at 4.375%, allows the place to cashflow nicely.. all things being relative.

Lastly, cities/towns that have well thought out city planning and/or strict zoning if combined with the aforementioned characteristics will almost always lead to supply pressures that work in your favor. 

Quote from @Alex Rodgers: Hi everyone,Cash flow is just a function of what down payment you use. 

Source: WikipediaSustained and significant population growth: Prices and rents are a function of supply and demand.

Combine that with appreciation and it could be a viable option.I also know of two different multi family properties right near the heart of Kailua Kona that are on the market as well.

Or a combination of other factors I'm not mentioning. 

However, I think if you decide to do this, you should get some money up front combined with owner financing so you have some skin in the game so to speak.

It is the only property that I own, and my reason for buying it was because I wanted to have the freedom of renting combined with an ok investment--and that's what has happened.