I think you're asking: As a landlord, should I offer a short term lease to see how they do?
I wouldn't.
I wouldn't (again) rent to someone "barely passing the threshold."
Unless I'm specifically aiming to offer social housing, to give a person a leg up, I would wait for someone who passes with flying colours.
I've seen people pass a probationary period, then let loose.
Also, please be sure to familiarize yourself with the landlord/tenant laws in your region *before* offering a place. So important!!