I know, and more importantly, some of the very best real estate attorneys in my state define a process that is 100% aligned with the law.

You have to make sure the people who you're working with have interest that are aligned.

You could make your employer contribution to your solo 401k as a traditional component and defer those taxes into the future.

You need two components: a deal and money.

The best chance for this deal to work will be to raise rents as justified to a level you feel comfortable with and then play around with reducing the $130 psf hard cost you cited to see if these factors align to make a feasible project.I have recently created a ground up development pro forma that can easily run this analysis and forms the source of the snap shots above.

While you still have to follow the rules of SDIRA in terms of prohibited transactions, self-dealing, etc, it has many more advantages:Compared to an IRA, Solo 401k contributions limits are roughly ten times higher.There is no custodial requirement for the 401k.You don't need the additional expense and administration of an LLC to have checkbook control.There is a built in-Roth component whereas IRAs are either traditional or Roth, not both.A spouse can also participate in the same Solo 401k plan.The Solo 401k has additional tax benefits over an IRA when investing into real estate using leverage.The penalties for prohibited transactions are less severe.Tax deduction, this plan allows contributions up to $61,000 per year per participant.

That being said, make sure you align yourself with someone (an agent) who either currently owns investment property, or has owned in the past. 

Less than $500 in repairs needed, 1 year warranty for most mechanical components, quality renters and PM in place are critical.  

Replacement and testing of underground components (instead of installation)3.

Funds work well for an investor who has found a sponsor that aligns with their values, strategy, time horizon and deal structure.