foreign diplomat as tenant, how to protect myself

[Mona Zemsky]

Hello, I'm lucky enough that a foreign diplomat is interested in a 4-year lease on my house in Chicago.  It's the incoming Consul General for the country's Consulate General in Chicago and his family.

A foreign national has no SSN, no credit, and no assets in the US, so an app/credit check is pointless.  The consulate won't make itself a co-tenant but has provided a letter on its letterhead that they are paying.  

The consulate is working with a realtor and so am I.  I already require a security deposit so the tenant has some skin in the game.

Any ideas for how landlords in this situation protect themselves?  Thanks in advance for any advice!