Yep, that was me. Thanks for the X-post, TX.
The mats are working out alright, so far. They do show show prints pretty easily, but they feel good underfoot. We haven't had snow in the past few days here, but the rain is coming down pretty hard and it's nice to have the lipped rubber in there.
If anyone is interested, I also got the trunk grocery hooks. part # 6y5-867-615--B41 .. about $15 each. Don't bother ordering the screws and clips, though. they won't fit in the S5. I used #8-32 1" machine screws and rubber push-in expansion fasteners (I think they are called Rubber Well Nuts). I got them at Home Depot and can post their part # if anyone is wants it.