You might utilize these extra cash for a down payment on a different house.Another good alternative is seller financing, which may be arranged directly with the seller and may entail a down payment and interest-bearing payments of the remaining amount over time.

How have you educated yourself on Infinite Banking, and on other concepts of financial planning that people could harness as part of their strategy as an alternative to IB? 

You might be able to work with them to support transitioning him somewhere he will be safer from himself.

My questions are around how to evaluate if its a safe/stable investment alternative? 

To find places with high rental demand, good economic circumstances, and room to develop, conduct in-depth market research.Examine your alternatives for financing, including conventional mortgages, private lenders, FHA, VA, and partnership loans.

Comparing the live-in flip approach to refinancing, the former offers the potential for higher profits through sweat equity but demands significant time and effort for renovations and alternative living arrangements during the process.

Considering your equity and cash reserves, exploring alternative financing options like traditional mortgages or partnerships might provide a more balanced approach to acquiring your investment property while mitigating risk.

Alternatively, you could open unsecured business credit lines and cards to tap for short-term use to cover down payments and closing costs (there's a company that specializes in helping real estate investors do this).

(alternatively does Vanguard offer self directed IRAs?)

Either make sure your partner gets 100 hours and you do 101, that way you get the benefit ;) alternatively you both can do 500 hours and both get the benefit.