I would first wait and see how they do. The floor mat are in a Class C, on both sides, is a pretty confined area, which may hold the mats in place without any other items needed to hold them down.
If they move, you may want to attach a clip to the seat floor bolts, that snaps on to the back of the mat.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor