I know many others have said this already, but it really does need to be repeated. This is an absolutely absurd request.

I wouldn't co-sign for a family member or best friend. Let alone someone I've never met who doesn't even have a stable, high-paying job secured in DC.

Your best bet is to find a private landlord and offer to pay several months in advance. You say you have over $6000 in savings. Good. Pay up to six months deposit on a relatively cheaper apartment and you should be good to go.

Good luck to you.