IS my rental opportunity worth it?

[Tyler Merrell]

I own 15 + acres in a rural community. My family and I can build homes and have done so for years. As we get older, we are looking at investment opportunities to supplement our incomes. My father is an architect/contractor, and my brother and I mid level+ carpenters.

Here is my question is it worth it? 

We are looking at starting small and building around a 1400 sq/ft, 4 bed/2 bath house. We will build it and will not pay ourselves for labor. The house will be appraised for $100,000-$130,000 using mid-grade material. Through our connections and labor the house will only cost us about 40-45 grand to build. We plan on getting a 30 yr mortgage at around 4.92 percent (this is actually 1 pt higher than offered). So if the house appraised at 100K we plan on re investing the other 55 to 60 grand in building a duplex (Duplex will cost about 35K 2 bed/ 1 bath each unit) in the area, once again no labor, and no mortgage on the duplex. We will have one mortgage payment at around $665 per month with property tax and insurance figured in. 

The house will rent for atlest $500 and the Duplex at least $350 per unit. That's $535 after NOTE and ins/tax. Is it worth it?( I figured in the lowest amount of rent but feel positive I can charge at least 650 for House and 450 for Duplex.) Oh yeah this will be a secluded neighborhood managed and ran by us. So kind of like a gated rental estate haha. 

If the House appraises for 130K of course we could build more house/duplex. Depending on exact budget. There are 3 of us investing and each of us are looking at building a 4 bed house and do the above mentioned......

Whats, yalls thoughts? I have researched the market well in this area and feel confident I can at least receive the rent listed. 

Should I Snow ball my mortgage since this is more of a long term investment of enjoy the lil earning now?