I may be displaying my ignorance here, but is there a way to BRRRR a note much like people do with physical real estate?

@Chris K.

I have saved 50 K cash and my house is paid off and currently worth 250 k.

Put together a Joint Venture agreement with someone that has an IRA or 410(k) that wants to make better money than they currently are making.

Big income with $10 K. 

here is my calculations with a 400 k down-payment and 850k selling price.

@Steve Vaughan The only debt I have is my mortgage and a few k in credit cards.

So, if you form SD-IRA multimember LLC, you have to pay tax annually by filing 1065 and K-1? 

@Jim K.  

@David M.As @Chris Tabanico indicated, a self-directed 401(k) is still a 401(k) style retirement plan, just with broader investment choices.When you retire from service, you will have the ability to rollover all or part of your TSP.