I'm not a resident of Illinois but have flown into O'Hare with a firearm transported per FAA regulations. I experienced no issues. What you describe would appear to be legal... but I'm not a lawyer and I post this for educational purposes only. You may want to see Illinois Carry's website...and also search for Fanny-pack carry.
See also: http://forum.opencarry.org/forums/sh...d.php?t=116183
Who in Illinois is Fanny Packing?
Since you have a license to carry, please note that this exempts you from FOID requirement. Illinois is odd in giving visitors a few more privileges than their residents.
Court case regarding FOID:
Full decision at : http://www.state.il.us/court/Opinion...ril/109130.pdf