In this case, the first lien will be held by the investor supplying the acquisition funds -- so what sort of security could I offer the investor(s) who would be willing to provide the $100K rehab funds?

These are basically deeds that state who the property will pass to upon the death of the owner.But in answering your question when there's a spouse living in the subject property (they may have held title as Joint Tenants) re-check the Notice of Petition and if there are other heirs/beneficiary's send your letter to them regarding the property.It's sort of like going through the back door if you will.

I've purchased a duplex and SFH so far this year (starting anew in real estate once again after divorce from 5 years ago), so my funds are sort of limited.

Beyond it making your home a hotel of sorts, I don't really understand what it is.

The stock brokerage I'm using isn't some sort of restricted retirement account with limitations on withdrawals.

I was lucky to be in contact through the seller by my family, and also this seller was really motivated to sell without going to the open market. 

Any extra money I earn from passive income will be donated or invested into some not for profit companies my wife and I have brainstormed.I am excited about meeting all sorts of people in the real estate investing community and learning from everyone!

But a reverse exchange sort of makes that work.In a reverse exchange the QI for the 1031 forms a holding entity called the EAT and purchases the new properties and holds them in title while you control them and operate them until you sell your old property. 

Seems doomed to fail in any sort of market correction. 

What sort of financing contingency to put on offers (what if my lender denies the loan based on the MFR income reported)?