Also, since new builds haven't hereto been my thing: What are the chances that a builder will let me sell/deed them the lot, build, and then I buy it back with a conventional mortgage (which I think may be the cleanest path forward if it would work)?

You really don't need agents/areas in your back yard- that's a myth).

Wholesaling as it's taught is a myth.

This can also be enhanced by rehabbing the property to get market rents.Regarding 1., I think this is a great place to start.

And up to the newer more enhanced codes to boot.

I conduct a few flips a year as well.Glad to see your using your skills to enhance your net worth and income.  

Equity and Risk Management: How might this structure enhance equity in the project and protect all parties involved?

Reach out to them.And here is a helpful overview of cost segregation myths: https://www.biggerpockets.com/forums/51/topics/1075919-five-...

However, using a self-directed individual retirement account (SDIRA) or an e-QRP (enhanced qualified retirement plan) for real estate investments comes with certain complexities and considerations.

I think where the book "The E-Myth Revisited" was great for explaining WHY you should have systems, Chad's article is excellent for a step-by-step guide for what to actually do as a landlord.