I put fifth's of liquor in the trunk under the floor mat all the time.. perfect for storing.. too bad you have those subs! Unopened or opened, just for transporting and since i'm only 19.. it's illegal to have anyways.. just never know when there's a party at my age! I've been stopped as well and never searched..

I would remove the styrofoam under the passenger carpet and cut out a little section for your flask.. it'd be perfect...!