Since the place you mentioned closed down, you're in a good place to get away with it. Having a good reference from the location you said you were "assistant manager" at could be the what makes or breaks you during the hiring stage. Find a friend that is smart and start roll playing the call that they're likely to get from a prospective employer.
You really are better off saying you've got a 4 year degree (if you feel comfortable saying this AND adding this to your resume)
Your story could be that you worked your way through college working at a fast food joint and eventually were promoted to assistant manager a year before you graduated.
Remember, only you can decide what you're comfortable fudging. The responsibility (and liability) is yours and only yours.
Good luck!