Looking underneath, it appears that once the bumper cover is removed, the receiver could be unbolted and removed, but I've only looked at it with the bumper cover attached.
After speaking with the parts dept, it seems that the hitch is sold in conjunction with the impact bar. I suppose they can be separated, not sure, but this is the part through GM for the receiver hitch. Explains their retail price.
Parts breakdown:
Wouldn't have to worry about cleaning up the rust in front of the hitch, but still worth trying a salvage yard for a good donor first.
I don't mind grinding away at the manageable rust in that area now, but hard to look away from a new unit....except for the price.