Alpine-
My hitch holes were close, the drive forward bolt was the toughest for me to get in, not to mention the passenger aft stud thread issue.
FWIW, I emailed Nashbar and told them their rack does not work without modification on the 2004 GTO. They replied by thanking me for my input and warned to not cut the rack!
I went ahead and stuck the cap back in mine but it may then be close to rubbing the bumper so I may go without it as the rack will then not hit.
I've loaded my bike on it and went for a two or three mile drive to test and it seemed fine. 110mph with a bike on back???!!

There are so many things to tighten I'm sure it's easy to forget to crank one down.
I used a couple of those rubber-coated hooks that you can hand screw into a bare 2x4 stud in your garage. I turned mine so that the hitch goose neck faces towards the indented spaces inbetween studs. This seems to stay out of the way pretty well.
How about the six clear stickies....did you put them on the seat post claws? I don't think they'll last long at all. Directions with this unit were a little vague as well. I do like that they threw in a little tool kit also.