Seems sketchy, have to take into account the low credit score. 

Should I do a cash out refi and potentially hurt my cash flow so that I can use the funds for another deal or two.

When it comes to pulling credit and background checks, TransUnion SmartMove is a solid option for independent landlords—it’s easy to use, FCRA-compliant, and the applicant pays the fee directly.

I understand the process and the incentives.Since the guidelines include a maximum percent of monthly income allowed to go toward housing, say someone making $5,000 a month with good credit and along other good credit items, can spend 35% of their monthly income on housing.

The bank letter of credit guarantees the bank will pay the amount of money required.

They aren't going to have good credit or a lot of income, so what would be good screening requirements? 

I am currently looking into applying for a credit card in hopes of liquidating the credit limit via bank transfer, and I am curious if anyone has experience doing that.Main concerns:1) How badly does it ding personal credit?

It’s rarely the ARV math that kills an investor.It’s not usually the contractor bid (though those hurt).It’s not even paying a little too much. 

My perspective is that if applicants had good credit they would buy rather than rent. 

Look at the credit report, there is probably a LOT more going on!