Need advice on buying second income property.

[Chad S.]

My wife and I bought a duplex in 2012 with an FHA Loan. We lived in half for the required 12 month then moved out and rented to establish the second rental. It now cash flows 1050/month and has appreciated roughly 30k on a conservative valuation.

We are looking to build / buy a fourplex now, I was hoping to get some advice and input on how to proceed. (Full disclosure my plan seems quite unconventional but if it works it could be ingenious)

Little background

 - I work full time earning 125k a year 

 - I am also a Realtor in my off time (Got licensed last year only made 30g)

- Duplex payment is 2300 rents are 1700 and 1650 

- I purchased for 329k owe 314k I would appraise for 365 in today's market

- Credit Score is average 690-710 depending on agency 

- Our family size has grown by 2 since we closed on the duplex. 

 - I bought a 2.5 acre piece of multi family property last year for 45k, I then subdivided it sold half 1.25 acres ( due to the scarcity of the multifamily zoned land I was able to get 50K for it)

 - I work with a builder in my brokerage who builds multi-family homes. As a Realtor I will be able to double side the transaction at 6% commission.   

 - The builder builds these fourplex's for 550k (That includes a 50k lot allowance) 

- Units rent at 1400 each. 

The Plan

The idea is to use the land a part of the down payment 50k (Builder buys lot from me to build on) Plus the Commission 33k

The gives me 133K when counting the 50 from the other half of the lot that I sold. 

This should give me enough funds to pay 20% on conventional owner occupy. I could toss my closing cost on top as these appraise at 575 all day.

The questions

Is this smart? 

Should I use up most of my cash or try and leverage using as little cash as possible and try to go FHA again do to the famliy size increase?

Any obvious pitfalls that I am overlooking?

Any advice going forward is greatly appreciated.