I have an ‘03 and have the same problem/question. After I attach the two snaps the rubber insert tab just seems to lay right behind the seat. I originally tried laying the boot cover on top of the black rim but it didn’t lay as flat as I liked, so readjusted and tucked it in all the way around the outside and it lays great, looks super. I know it should probably be left out, but didn’t feel secure enough or look as good. Know this doesn’t answer the total question, but I have showed this car and no one said a word. Have won my class a few times as well....one day, someone will notice and explain I guess..

 

The way I did mine was immediately after I bought my car, I folded the cover back up and stuffed it into the attic where it has sat for the last 12 years.