From what I saw.....
I dont actually own the covers yet, because I wanted to figure out the arm rest issue before I got them.
They are not open back. I dont know the amount of slack. - The issue of the size of the plate brings up an interesting idea. Do you think If i was to cut the pile of the sheepskin around the edge of the "plate hole" I could tuck the cover fabric in, and use the attachment to bascially lock the cover in place around the plate.
I dont know if you understand what I'm trying to explain, but basically have the plate mount on the cover, with the cover tucked in underneath it, rather than have a hole in the cover for the plate that is not finished.