I was trying to produce something similar using Zillow's APIs but I couldn't find parameter that would give the HOA fee.

This would actually be a great opportunity to sell the duplex...and buy a large apartment building since you have so much equity and they tend to produce better income . 

(c) A water supply approved under applicable law, which is:(1) Under the control of the tenant or landlord and is capable of producing hot and cold running water;(2) Furnished to appropriate fixtures; and(3) Connected to a sewage disposal system approved under applicable law and maintained in good working order to the extent that the system can be controlled by the landlord.

Clean water and local produce. 

Our first went better than expected, currently producing $1100/month net cash flow, around $50k equity upon stabilizing.

So now i would have an income producing property owned outright worth 30k.

I wouldn’t waste my time on anything that doesn’t produce atleast 2% .

The idea is that over a long hold period, your expenses on an investment property if you track them very well will tend to gravitate to about 50% of the income it produces. 

Im looking for a single family home in houston texas that could produce passive income.

There is no deals in Hawaii that produce cashflow.