Since it hasn't been mentioned(from a designer's stand point) egress is a means of exit, and speaking from Wisconsin Uniform Dwelling Code, (IRC is in the mail), there has to be two exits from habitable space.
Is there a stairway to the garage AND to the upper floor,(those would have to be more than half the longest diagonal of the basement, apart).

I agree that little stairway is a hoot...
Our State requires 20"x24" (either way)-5.7 sq. ft. which still does not help your situation, but the rest might help shed some light on egress req.
Not to mention I'm trying to get my posts up...