Keep in mind that LLCs were originally devised for groups of investors to pool funds for a business venture and then hire out the day to day running of the business. 

The better way to think about rentals in an IRA is whether such opportunities provide a better mix of principal security and opportunity for growth than other things the IRA might invest in.In addition to using leverage (something your IRA is not benefiting from today, most likely), you can joint venture with other partners on a property transaction, you just have to avoid disqualified parties to the IRA such as yourself, your spouse, and lineal family.   

When venturing further from downtown, the school districts change .

I'd start there and then venture out into some of the specific industry versions if desired.

In my layman's opinion, I thought the sale of land was generally an active trade and here is where the Winthrop factors specifically apply (since it was a a ruling about raw land as I have been educated in BP).I assume this is a multi-year venture. 

I'm looking for suggestions on how how to fund a venture of this size. 

Yeah you can do a joint venture between the two LLC's if you have high trust (looks like it's your brother so hopefully that is true).

Now you have a vested interest in the venture. 

Only problem I see with that data regarding San jacinto is id venture to say it’s as high as 90% of the neighborhood that is sold “off market” and hard to track. 

I havent ventured into the multifamily stuff but maybe one day.