sleeve=bad idea
bending the hangers=the way to go
also, what exactly is the exhaust rubbing on? is it a heat shield or part of the frame?
you said "crossmember" which makes me think the front, but you also said "before the axle" which makes me think the rear. I had some rubbing issues with my corksport exhaust which I easily fixed once I pinpointed the problem area.

 

^^^

Yup! It's in the rear. Man it drives me crazy because I know if i can hear it, everybody else can too!!

 

ok.... we've narrowed it down to "in the rear"

now let's try to identify the exact part of the car that it's rubbing.