I managed to get the thing replaced. I had to sit upside-down in the passenger seat, with the seat fully reclined, my head in the footwell and my feet at the top of the seat. For a few seconds after I got the cover off, I was concerned I wouldn't be able to extricate myself, but I managed. I didn't want to revisit that position after swapping the filters out, so the cover isn't very well secured. I've ordered the
Abstract Ocean magnetic cover, and I figure I can survive a loose cover for a few days until it arrives.