What?!? I just suggested to cut the thing straight, which probably costs less. And include the other piece separate. Or better yet, charge less for the sub one, and a little extra for the larger piece. The other piece doesn't have to be attached together. But whatever. I wouldn't get it like that, but hopefully I'm just a minority .Why? Cost for one thing. These mat requires a proprietary system to infuse each layer so there is no glue being used.
As a side comment, at least my 2019 car has a pretty hefty pad attached to the bottom of the trunk cover, so that's probably why I don't hear that much noise from the trunk. I'm not going to add extra weight, and reduce trunk space unless it's needed, and right now, it's not. But yes, I'd love to quiet the road noise from the front first, then tackle the rear, if needed.