6 Months in Advance in Rent

[Carlos Rodrigues]

Good evening!  I have a unit for rent and I came across some potential tenants that want to rent the property.  They keep calling and stoping by the property to talk.  My only concern is that they are undocumented, and so I believe I can not check there background, credit check, etc.  They did offer to get a Co-signer and they're willing to pay 3-6 months in advance.  Should I take the 6 month in advance in rent or no?  Any additional tips when it comes to renting to the undocumented?