From his Facebook I found out he recently retired as a mortgage broker. 

Long term, look to semi retire but thats a long way off and by then my needs might change.

BP also has quite a few active (I am one) , retired or former military members that face similiar challenges to you , and can help identify some military and VA benefits ( VA loan being the big one ) you can useKen

The duplex is fully occupied which seems like a fluid transaction for me as I'll be taking the handoff from the owner. the current owner would like to retire from land lording and wants to get rid of it.

The make up of this purchase will be Retirement Trust - ( My solo 401k)My brother in lawAnd a 3rd personWe are wondering if it is better to form an LLC, or just have the OTP show the three entities/people. 

I mean it's funds you can't live off of until retirement but I am much happier controlling and earning much greater returns than I was in a stranded 401k plan.You definitely want to go the full LLC route so you can have checkbook control at your local bank rather than having to go through the self directed IRA company to make all the purchases.

@Susanne RiethYou are correct, a self-directed IRA or 401k can be used to do alternative investments such as buying a rental property, however because you are considered to be a 'disqualified person' to your retirement account you are prohibited from receiving any personal benefits as a result of your investment activity and also not allowed to provide any services to the plan. 

No - I still have a "Real Job" and can retire with a pension as early as January 2019- but will probably stay a bit longer to increase my pension benefit and insurance copay %%.I do spend at least 40 hours a week on my rental business - I am non-stop from January thru July and this is now the off-season.Renata

But I am not betting my retirement on it. $55k is a solid amount of money to start your journey. but turning that into $1M will be full of twists and turns and many years of making good decisions.

Long story short(not really)- Relocation due to job transfer required due to spouse being medically "retired".