Usually a few % in pre-paid interest, insurance, appraisal,  inspection, title and escrow fees.  

Could consider part of it prepaid legal advice!

Fees to close escrow on a home include costs such as origination charges, appraisal fee, home inspection, title search and lender insurance, prepaids (such as homeowner’s insurance and prepaid interest), and title insurance.After taking title and moving in, the part of the property being rented out will need to be made ready for a tenant.

@Miguel Vasquez I work for a rent payment service and one option we recommend for tenants without a bank account is a prepaid debit card that allow ACH debits, such as the NetSpend card.  

These fall into three categories: lender charges, third-party charges, and prepaid items.

(There’s probably prorated taxes and prepaid escrow amounts.)

This is assuming rates stay within about 2%, and you can usually buy down interest (which is pre-paid interest and tax deductable).

Down payment+lender fees+credits+prepaid debits(insurance+taxes) ?

So what's left is god old human trust and maybe the threat of a bad online review.You can only limit your exposure, like you said, maybe a prepaid credit card etc.

@Jonathan Davis- great  ...as  you have a primary home  - you will need to amass  a down payment of  at least  15%  for a rental property  purchase ....there will also be  closing costs / prepaids / loan fees  ....work on  savings  funds ....get  pre approved  so you know  the  numbers  needed for  what you want to do