So the risk is lower, as long as the market doesn't drop 20% and stay that low for the next 3 years. 

Nashville is a ridiculously competitive market.

Here’s our OPINION for the Metro Detroit market (use as a template for your target area!)

If things go sideways, you discovery greater rehab expenses, the market takes a turn for the worse, you can get in the red quickly. 

This year I may see if if I can get a construction loan to build 20-30 apartments, then refinance with an asset based lender. what markets?

Since it is a family member and I would potentially buy the property for under market value.

My first duplex was a turnkey, off market property.

This is one of the main inherent risks with pre-construction, and the pre-construction market has cooled, and with impeding tariffs, there is some uncertainty around where prices will be in the coming months.One thing to clarify, are you looking to buy an investment property or a primary residence (or perhaps abit of both where you live in one unit and rent out the other)?

Any advice on starting out on this in the Houston or Katy market?  

However my market is currently Arizona.