OMG this post is giving me anxiety. Starting your first ever home build of this magnitude, with hard money loan, and no knowledge of house to build a house is quite a risky venture. This isn't a $100 lego kit you are building this is a 1.5 to 2 million dollar home and have no idea how to build one. This price point, location is not all that matters. Finishes and design are huge for this level of buyer. I have no business giving advice on this as I never built a home. I know all the steps to do it, time frames it takes, and various contractors needed due to working in the building industry for 20 years but would never jump this far in my first time building an investment home. That said hard to say what happens with market but if things begin to shift that is when people who have no idea what they are doing usually suffer the most because they are taking the biggest risks. I suggest you find someone who actually knows what they are doing, reach a deal where you provide the lots, they build on them and you split the cost. Setup a contract that protects you. Way to many areas you could end upside down and loose everything. I hope it works out for you but this whole thing scare the crap out of me for you. People make plenty of money building house that have no idea how to build a house. I work with many of them. However, they are smart enough to surround themselves with the right people who do know what they are doing and everyone benefits.
Good luck sir. You got a lot ahead of you. Sincerely hope it all works out for you.