Greetings,This is likely a silly question, but are hard money lenders ever willing to fund 100% of a down payment on a large purchase (20+ units) after viewing the deal (rent rolls, etc)?

Last option is to sell them - do a 1031 and roll your proceeds into a better performing property. 

Since I will be leaving my corporate job and effectively self-employed as I manage most of my MF portfolio, can I roll my retirement savings into a Solo 401k and invest in RE with the money?

So if you do just #4, make sure your cash is in some rolling balance that accrues the 4-5% HYSA or tbill or fixed income to mitigate the loss spread of your debt servicing rate + negative cash flow versus your apy. 

I strongly suspect your best move is to roll the TSP to a Traditional IRA and convert the IRA to a Roth, using non-retirement dollars to pay the income tax, even if you have to borrow the tax liability.

Yeah, house hacking is a great way to get the ball rolling.

Side Note: Up front capital from my side is not an issue for down payments, and leaning towards the fix and flip strategy to build some cash and roll into a 1031 to ultimately get into the multi family space.  

If not, we’ll need to have one ordered for you.Entity Documents (NEEDED FOR PREAPPROVAL):LLC/LLP i.Copy of Articles of Formation/Incorporation ii.Copy of fully executed Operating Agreement/Partnership Agreement (all pages & amendments) iii.Certificate of Foreign Qualification (if applicable) Corporation i.Copy of Articles of Formation/Incorporation ii.Copy of fully executed Corporate Resolution designating authorized signer(s) for the Corporation iii.Copy of fully executed Corporate Bylaws iv.Copy of stock certification v.Certificate of Foreign Qualification (if applicable)Identification (NEEDED FOR PREAPPROVAL): Copy Driver’s License or Passport for each Guarantor.Rent Roll (NEEDED FOR PREAPPROVAL): We’ll need to get an understanding of the current cash flow of the property.

I'm a real estate agent, investor and developer in central Houston and I'm happy to answer questions that you may have as you get rolling. - Chris Kersey 

@Sean OToole  has built an awesome product and I believe they are rolling out nationwide either soon or shortly..