You definitely want to use a thorough screening method like rentprep.com that gets their income, credit, background check, and call at least 3 references (make sure to verify them by address/job and then their name).  

Chris, I work full time remote and specialize in land.

The property value must be a minimum of $250,000 USD, and the credit score requirement is at least 700 points, among other conditions.

If you're not having any luck with mortgage brokers (I'd search out the ones who specialize in investments), then go to your local REI meeting. 

True re the prior poster, re this helping the seller save their credit, if you buy sub-to you will dramatically raise their FICO since the mortgage will show on-time payments.  

Shaq doesn't get half the credit he deserves for his business savvy.

Can easily get fee worksheets and run credit/DU 3.

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Specifically, I am looking at partnering with an individual who owns securities (stock and mutual funds) having them take out a line of credit against their portfolio (SBLOC) at a low interest rate, and using that to purchase properties rather than using a mortgage.

She is a Baltimore agent that specializes in househacking