The end goal is to minimize reliance on "traditional" working hours, while building equity in long-term properties.

Watched Marcus Lemonis on the profit and it seem you can invest in food trucks for  a cheap price and put the owner and some workers in there and take a cut of the profit as an investor.The traditional restaurants you have to drive very high sales per sq ft.

While you might have to sign a contract after the auction, it would not allow you the time to obtain traditional financing.A bank would never approve you for a mortgage, give you cash directly, and send you on your way to look for a home to spend that cash on.  

Do you know of an independent bank that gives reasonable rates and takes into account your rental homes cashflow and history unlike traditional banks?

The area is traditionally rural, but has brought in two major companies in the last few years and is quickly outgrowing its available rental housing.

This is difficult because 85% of real estate closings are traditional mortgage loan closings.  

I am going to assume you don't declare that income to the IRS on your tax return and pay the proper amount of taxes on it.If it is not on your last two years of tax returns,you will get no credit for it from the traditional banks and lenders which means you ability to borrow money will be based solely on what little you do declare and have taxed properly.Your savings and checking account s and stock holdings are irrelevant,only your verifiable monthly and yearly income.Your only choice would be a hard money lender at an enormous interest rate.

Not going to be traditional Fannie/Freddie backed loans.

With the SDIRA, or Solo401k, there are restrictions of it being "non-recourse" meaning no personal guarantee from you, which make them hard to find through traditional lenders.

Many of the guys I know in the business have gone and got their real estate license and are making more money doing traditional real estate deals.